Abstract (English):
The notion of project leadership is considered to be one of the most popular topics among both researchers and managers. However, the question of whether transformational project leadership (TFL) or transactional project leadership (TAL) is more efficient for organizations is widely debated. The aim of this study is to provide an overview of the tendencies in the research of TFL and TAL in 2016–2019. This study was based on literature review and selected research articles of each year from Scopus according to particular metrics: article citation index, author h-index and journal CiteScore. A questionnaire among experts was conducted in order to evaluate the relationship between the metrics. The main contribution of this study is that it unites research papers of a different focus and offers insight into the key findings on the notions of TFL and TAL in the last four years. The study shows that TFL and TAL were found to have both positive and negative implications under certain factors and circumstances. Furthermore, the study indicates that TFL and TAL do not oppose but rather complement each other. Hence, the balance between TFL and TAL is likely to be an optimum choice. Limitations of the study and recommendations for future research are thoroughly discussed in the paper.

Keywords:
transformational leadership, transactional leadership, project leadership, leadership styles, leadership effectiveness

INTRODUCTION

Over the past decades, the notion of project leadership in the workplace has become the subject of various studies. Today there is sufficient evidence of a positive linkage between an effective leader and a company’s performance [Lipponen et al., 2008; Tafvelin et al. 2014]. In order to have a successful group project and maintain the sustainability of an organization, it is essential to assign a leader who will create shared visions and goals and navigate a team [Outhwaite, 2003].

Scholars usually differentiate between two project leadership styles: transformational leadership (TFL) and transactional leadership (TAL). Prior studies mainly focused on either a particular scope of an organization — education [Al-Husseini, Elbeltagi, 2016; Aydin et al., 2013], supply chain [Birasnav, Mittal, Loughlin, 2015; Mokhtar et al., 2019], etc. — or on a particular organizational outcome — creativity [Hermann, Felfe, 2013; Kim, Lee, 2011], conflict [Doucet et al. 2009, Dussault, Frenette, 2015], etc. The studies based on literature review in terms of project leadership are also present. Xie [Xie, 2019] collected data from articles to examine the connection between project leadership and organizational learning culture, whereas Yahaya and Ebrahim [Yahaya, Ebrahim, 2016] investigated the effect of project leadership styles on organizational commitment. Though no studies exist that have had a more holistic approach and offered insight into the concept of project leadership styles regardless of a particular outcome or the sphere of an organization. We also have limited knowledge of how the research on TFL and TAL has developed. Furthermore, the debates on the impact of TFL and TAL are still present since the data of different scientific articles contradict one another. Some studies stress the positive effect of TFL on various outcomes in the workplace [Chang, Lee, 2013] while others demonstrate that TSL might have a more positive influence [Masa’deh, Obeidat, Tarhini, 2016].

This research aims at examining studies published in academic journals to discover the tendencies in the research of TFL and TAL over the last four years. Its main objective is to provide an overview of how the scope of the research has changed through the years and what the correlations among different studies are. The theoretical value of this research paper is that it unites several studies and represents the main trends in terms of TFL and TAL in the course of time. The practical value of this research paper is that it may serve as guidelines enabling project managers to choose their leadership style correctly. The remainder of this paper is organized as follows. The next section briefly explains the essence of the two main dimensions of project leadership. In the third section the methodology and methods of the study are thoroughly described. This is followed by outlining the results of the methods used. The fifth section discusses the features of each year and pinpoints the main trends. The final section is concerned with limitations of the study and suggestions for future research.

 

CONCEPTUAL FRAMEWORK

This paper builds on the seminal papers of Bass, 1995; Bass, 1998; Bass 1999; Howell, Avolio, 1993; Judge, Piccolo, 2004; Podsakoff, MacKenzie, Moorman, Fetter, 1990; Seltzer, Bass 1990. The search for an identification of the behaviours that increase a leader's effectiveness has been a major concern of practicing managers and project leadership research for the past several decades [ Bass, 1981; House, 1971; 1988; House & Baetz, 1979; Stogdill, 1974; Yukl, 1989]. Traditional views of project leadership effectiveness focused primarily on what Burns (1978) and Bass (1985) have called transactional leaders behaviour [Podsakoff, MacKenzie, Moorman, Fetter, 1990] Burns pointed that transactional behaviours are founded on an exchange process in which the ladder provider reward in return for the subordinate's effort [Burns, 1978; Podsakoff, MacKenzie, Moorman, Fetter, 1990]. More recently the focus of leadership research has shifted from one of examining the effect of transactional leadership to the identification and examination of those behaviours exhibited by the leader that make followers more aware of the importance and risk outcomes, activate their higher-order needs and induce them to transcendent self-interests for the sake of organization – TFL [Bass, 1985; Podsakoff, MacKenzie, Moorman, Fetter, 1990; Yukl, 1989]. The comparison between TFL and TAL has been widely discussed in researches through the past decades. [Avolio & Bass, 1988; Bass, 1985; Bass, Avolio, & Goodheim, 1987; Bass, Waldman, Avolio, & Bebb, 1987; Bennis & Nanus, 1985; Boa1 & Bryson, 1988; House, 1977; Conger & Kanungo, 1987; House, Spangler, & Woycke, 1989; House, Woycke, & Fodor, 1988; Howell & Frost, 1989; Shamir, House, & Arthur, 1988; Tichy & DeVanna, 1986]. Futhermore according to research made by Timothy A. Judge and Ronald F. Piccolo in 2004 «A search of keywords in materials published from 1990 to 2003 in the PsycINFO database revealed that there have been more studies on transformational or charismatic leadership than on all other popular theories of leadership (e.g., least preferred coworker theory, path-goal theory, normative decision theory, substitutes for leadership) combined». [Judge, Piccolo, 2004]

Previous research has shown that the TFL style has been effective for the employee’s retention within the companies and engagement while TAL tend to negatively affect employee’s performance. It was claimed that TFL style has a positive impact on the employee’s motivation, efficiency and creativity and TAL has been found to enhance job satisfaction compared with TFL [Epitropaki & Martin, 2005; Bronkhorst, Steijn, & Vermeeren, 2015; Gong, Huang, & Farh, 2009; Kark, Van Dijk, & Vashdi, 2018; Laschinger, Wong, & Clarke, 2018; LePine, Zhang, Crawford, & Rich, 2016; Newland, Newton, Podlog, Legg, & Tanner, 2015; Vasilagos, Polychroniou, & Maroudas, 2017].

 

However, it is also claimed that transactional and transformational leadership can complete with each other creating an augmentation effect which stipulates that TFL leadership adds to the effect of TAL. [Judge, Piccolo, 2004]. This suggest a dilemma if TAL and TFL can complement each other and if they do what is the conflux between TAL and TFL for an effective leader. Some researches state that TFL is preferable above TAL; some imply that without the basis of TAL, the effectiveness of TFL is unreachable and others claim that TFL adds beyond TAL but not vice versa. [Judge, Piccolo, 2004]. This effect was described by Bass [Bass, 1998, p. 5] as the level to which «transformational leadership styles build on the transactional base in contributing to the extra effort and performance of followers». In another article the researcher also pointed that «the best leaders are both transformational and transactional». [Bass, 1999, p.21] This point was also discussed by Howell and Avolio who stated that TFL complements the TAL and that the leadership efficiency is gained by the supplementation of TAL by TFL. The key point of their theory was the necessity to build TFL based on TAL [Howell, Avolio, 1993] This theory was commented by Bass in 1998 who stated that «transformational leadership does not substitute for transactional leadership» [Bass, 1998, p. 21]. After that Avolio wrote commented «transactions are at the base of transformations» [Avolio, 1999, p. 37]. Bass conceptualized TAL as the instrument that gives meeting follower’s expectations «upon which their end of the bargain is fulfilled, and they are rewarded accordingly» [Judge, Piccolo, 2004].

 

LITERATURE REVIEW

Project leadership style is a pattern of behavior that encompasses certain traits. In this research, two main forms of project leadership are singled out: TFL and TAL [Burns, 1978]. B. M. Bass [Bass, 1985] also identifies a third style known as laissez-faire leadership which denotes a leader with poor guidance and support, absence of decision-making and avoidance of participation. It is described as a “non-leadership style” [Dussault, Frenette, 2015, p. 725] and thus sometimes omitted in data collection [Avolio, Bass, Jung, 1999]. Additional profiles of project leadership were also examined in some studies. For instance, Kelly and Macdonald [Kelly, Macdonald, 2019] in their research employed another classification devised by Lewin et al. [Lewin, Lippitt, White, 1939] and Yukl [Yukl, 2002] and explored such styles as authoritarian, democratic, bureaucratic and laissez-faire.

The underlying premise of TFL is that it encourages employees to achieve goals and perform beyond expectations. Transformational leaders usually display several models of behavior: charisma, inspiration, intellectual stimulation and individualized consideration [Burns, 1978; Bass, 1990]. Charismatic leaders create a sense of mission while being an inspirational leader implies communicating high expectations and enthusiasm. Intellectual stimulation focuses on boosting creativity among employees. Finally, the idea of individualized consideration is in regarding employees as individuals and utilizing different approaches depending on their needs and personalities. Later, Bass and Avolio [Bass, Avolio, 1994] reconsidered the dimensions and replaced charisma with idealized influence. It is possible that some of the components in the behavior of a transformational leader are absent. During the last decade such term as pseudo-transformational leadership has come in the spotlight. This model of management is usually characterized by unethical behavior, egoistic values and self-interest [Lin et al., 2017]. A pseudo-transformational leader exploits transformational patterns of behavior to achieve their own agenda.

Conversely, TAL is a “give-and-take” relationship in which employees focus on meeting requirements. The key attributes of TAL are contingent reward and management by exception [Bass, 1985; 1990]. Contingent reward is a positive feedback from a leader if a subordinate completes assignments properly and meets expectations. In contrast, the use of negative feedback in case of employees’ underperformance constitutes management by exception [Dussault, Frenette, 2015]. Management by exception may be further divided into active and passive. Active management by exception is used to denote a leader who actively monitors employees’ performance and takes measures prior to severe problems whereas in passive management a leader takes measures after problems have occurred and does not respond to them systematically [Clarke, 2013; Yahaya, Ebrahim, 2016]. The core difference between TFL and TAL lies in the motivation that subordinates have. Transactional relationships are based on the exchange in which employees are stimulated by compensation for their performance, whereas TFL enables employees to identify themselves with the goals and interests of a company and thus have stronger nonmaterialistic incentives [Buil, Martinez, Matute, 2019].

The first model of measuring TFL and TAL based on six factors was proposed by Bass [Bass, 1985]. The model called the Multifactor Leadership Questionnaire (MLQ) was further modified and some factors were added [Avolio, Bass, Jung, 1999; Avolio, Bass, 2004]. Although the MLQ has been criticized by some scholars [Van Knippenberg, Sitkin, 2013], it is still regarded as one of the most popular methods of measuring TFL and TAL and was validated in some previous research [Avolio, Bass, 2004; Rowold, 2006]. It usually consists of 36 items and makes use of a 5-point Likert scale [Van Jaarsveld, Mentz, Ellis, 2019]. However, in some studies the structure of the model can be significantly modified: either extended or reduced [Dussault, Valois, Frenette, 2007; Dussault, Frenette, 2015].

 

METHODOLOGY

While previous studies mainly made use of empirical methods and focused on the measurement of certain aspects of behavior (e.g., [Masa’deh, Obeidat, Tarhini, 2016; Xie et al., 2018]), this paper had a more theoretical approach. In order to pinpoint the trends in the research of TFL and TAL over the last four years, a variety of methods were employed. To receive a general picture of the research in this field, it was decided to pick 10 most representative scientific articles from each year and conduct a thorough analysis of them. Scopus was chosen as a platform as it has a more significant number of studies devoted to the social sciences in comparison to other sources [Aksnes, Sivertsen, 2019]. Although Scopus is criticized for its shortcomings, such as an absence of articles before 1996 [Harzing, 2010], it was of a minor importance for our research. The representativeness of the articles was measured based on three key dimensions that platforms usually provide: article metrics, author metrics and journal metrics. We opted for this strategy of article selection as citations have been considered reliable while evaluating the quality of research [Van Raan, 1996; Borgman, Furner, 2002]. Since many research papers demonstrate that the information on the metrics mentioned vary substantially on different platforms, all figures were taken from Scopus to reduce any disparity [Ball, Tunger, 2006; Harzing, 2010; De Groote, Raszewski, 2012]. In order to establish a correlation between the three metrics, a survey among experts was conducted. Although other factors that may contribute to selecting articles, such as awareness of a journal or an author and skimming through abstracts, exist, this study had a more standard approach. The two methods used are described chronologically in more detail as follows.

Survey. The survey made use of a questionnaire on a Google Form which comprised five questions (Appendix). The first two questions required some general information about a respondent (age, gender) while the remaining concerned the credibility of such indicators as ‘article citation index’, ‘author’s h-index’ and ‘journal CiteScore’. A seven-point Likert scale was adopted for the respondents to measure those factors from “absolutely not credible” to “absolutely credible”. The time required to fill in the form was approximately three minutes. The link to the questionnaire was randomly sent via e-mail to the professors of National Research University Higher School of Economics who have at least one publication in a Q1–Q2 journal. In aggregate, 80 questionnaires were distributed digitally and 31 responses were collected (39% response rate). In the sample, the age of the respondents varied from 32 years to 89 years and the average constituted 46 years. The majority of the participants were male (81%).

Article selection. On the period 2016–2019 the first 30 articles were selected from each year based on their citation (from the highest). The articles were extracted from Scopus with the help of the advanced search form and the command “TITLE-ABS-KEY (“transformational leadership” AND “transactional leadership”) OR TITLE-ABS-KEY (“transformational” AND “transactional” AND “leadership”)”. We regard this command as the most optimum as it shows the articles dedicated to both TFL and TAL. Moreover, it includes the papers which did not use the notions of leadership styles in their keywords as the command scans abstracts as well. Further, the table with the list of the articles was compiled. It incorporated such information as the paper’s citation index, the highest h-index among the authors of a particular paper and the CiteScore 2018 of the journal in which the paper is published. The data from Scopus were taken on the 25th of June 2019. Hence, any changes in the metrics after this date have not been considered. It was supposed to employ the formula devised from the findings of the survey among the experts in order to pick 10 most representative papers from each year.

 

RESULTS

Means, mode and standard deviations are presented in the table.

Table. The descriptive statistics of the questionnaire

 

	Valid N	Mean	Median	Mode	Frequency of Mode	Std. Dev.
Citation index	31	0,348	0,333	0,333	11	0,064
Author’s h-index	31	0,287	0,313	0,333	11	0,066
CiteScore 2018	31	0,365	0,333	0,333	11	0,065

 

During the statistical analysis of the survey results it was noticed that the coefficient of concordance constituted only 0,194 (19%) which demonstrated that the findings could not be employed for further investigation as the minimum is usually estimated as 60%. It may also imply that among the experts there is currently no clear understanding of how the three components should be treated. However, the mode constituted 0,333 (33%) which enabled us to consider the three indicators equally. Thus, the articles from the table were selected according to the sum of ‘journal citation index’, ‘author’s h-index’ and ‘journal CiteScore 2018’ based on the data provided by Scopus. It should be pointed out that although some papers employed the notions of TFL and TAL in their abstracts, their primary focus was different (e.g., [Grisaffe, Vanmeter, Chonko, 2016; Zehnder, Herz, Bonardi, 2017]). Hence, the final stage of the methods was a qualitative analysis of the selected papers on the level of their contribution to this study.

 

DISCUSSION

The following section discusses the research in TFL and TAL on each year of the studied period based on the most representative articles on Scopus.

Year 2016. The year is characterized by diverse studies devoted to different aspects, such as sport and athlete mentoring functions [Hoffmann, 2016], leadership training [Von Thiele Schwarz et al., 2016], etc. It is interesting to observe the correlation between TFL and TAL. As suggested, TFL is not opposite to TAL but rather additive to it which implies that TAL is more classical while TFL may be employed additionally to achieve better results [Hu et al., 2016]. This premise is in line with another research study of this year which called TAL “an essential precondition” for TFL [Asiri et al., 2016, p. 2].

The studies of this year demonstrate that the choice between TFL and TAL is to be contingent on some factors. The study of enterprise systems success established that TFL functions well during the adoption period. However, a switch to TAL is necessary in the implementation phase [Shao, Feng, Hu, 2016]. The notion of ambidexterity, which implies the employment of both exploration and exploitation, has been discussed in another research paper [Baškarada, Watson, Cromaty, 2016]. A parallel was drawn between TFL and exploration as well as between TAL and exploitation. In the study it is proposed that the balance between TFL and TAL behaviors is required. With regard to innovation, Prasad and Junni [Prasad, Junni, 2016] state that both leadership styles may have a beneficial effect. Nevertheless, TFL was found to be more efficient.

One of the papers in 2016 investigated the effect of leadership styles on leaders themselves [Lanaj, Johnson, Lee, 2016]. As it is pointed out in the study, only one research paper has examined the concept before as others focused mainly on either followers or firm performance. According to the findings of the paper, the behaviors reflective of TFL may have a positive impact on leaders by increasing positive affect and decreasing negative affect. It is also noted that the effects of TFL on leaders are more significant than of any other type.

Organizational commitment, which is considered to be essential for a company, was explored several times in 2016. In one literature review study it is emphasized that the previous findings show rather controversial data [Yahaya, Ebrahim, 2016]. The controversy may be also observed in two articles dedicated to healthcare. While one study indicates that both leadership styles are positively related to organizational commitment stimulated by decision-making and empowering [Asiri et al., 2016], another paper states that TAL decreases decision-making processes [Hu et al., 2016]. Furthermore, the findings of the paper devoted to surgery, which analysed knowledge sharing in the workplace, are not consistent with another paper of this year [Hu et al., 2016]. The former concludes that TFL stimulates information sharing, whereas in the latter the impact of only TAL on knowledge sharing was found [Masa’deh, Obeidat, Tarhini, 2016].

Year 2017. In the research studies of this year some new topics were advanced: leader’s regulatory focus [Johnson et al., 2017], employees’ entrepreneurial behavior [Afsar et al., 2017], etc. Some tendencies are to be singled out. First, several studies explored the linkage between leadership styles and innovation. It is proposed in one study that innovation-oriented strategy is positively correlated with TFL. Nevertheless, utilized with transactional leadership the strategy is not beneficial [Stock, Zacharias, Schnellbaecher, 2017]. Moreover, Liu and Chan [Liu, Chan, 2017] urge that individualized consideration as one of the components of TFL can foster follower innovation only with the presence of high support for it, while intellectual stimulation requires high performance self-efficacy as well. Finally, contingent reward as one of the dimensions of TAL may foster innovation under leadership-performance self-efficacy. The research is interesting in that it made use of a more detailed approach by investigating not the notions of TFL and TAL as a whole but rather their components. It indicates that the boundaries between the two concepts are blurred and thus a more developed leadership-innovation model is required [Liu, Chan, 2017]. It also supports the premise that TFL and TAL are by no means the opposite terms. According to [Zheng, Wu, Xie, 2017], both leadership styles are positively associated with innovation and influence it either directly or indirectly through knowledge sharing. It is also emphasized that TFL should be introduced at later stages in a project.

Some articles examined the connection between leadership styles and enterprise resource planning system (ERP). The findings of the papers suggest that both TFL and TAL are positively related to ERP [Rezvani, Khosravi, Dong, 2017; Shao, Feng, Hu, 2017]. In the first paper the authors argue that the leadership styles may influence user satisfaction and perceived usefulness which will eventually stimulate employees to engage with the system [Rezvani, Khosravi, Dong, 2017]. The second paper [Shao, Feng, Hu, 2017] stresses that, contrary to TFL, TAL has a weak but direct influence on ERP. It is also recommended to employ a combination of the two styles during the assimilation phase.

The problem of safety in an organization was also popular in 2017. In one article it is revealed that TFL, as well as active TAL, has a positive effect on safety in the construction industries whereas laissez-faire leadership is negatively related [Grill et al., 2017]. Another study pinpointed that the effect of the leadership styles is contingent on “followers’ perceptions about the likelihood for an accident”: when the likelihood is regarded as high, management-by-exception active (the component of TAL) proves to be efficient, whereas TFL is appropriate on the condition that followers’ perceptions of an accident is not significant [Willis et al., 2017, p. 281]. Finally, the concept of commitment was discussed in one research paper of 2017 in which a positive correlation between the two leadership styles and organizational and safety commitment was found [Delegach et al., 2017]. This conclusion is in line with the study from the previous year [Asiri et al., 2016].

Year 2018. The year mostly comprises articles that refine some aspects of the previous research: innovation, safety, etc. Among new topics emotional intelligence [Zhang et al., 2018] and quality performance [Teoman, Ulengin, 2018] may be singled out. As far as innovation is concerned, one study revealed that TFL is positively related to it while TAL has a negative impact [Jia et al., 2018]. Hence, the authors recommend that for innovative performance-oriented companies it is imperative to employ TFL. The findings are in line with the previous study [Stock, Zacharias, Schnellbaecher, 2017]. Another research paper emphasizes that although both leadership styles may contribute to the creation of innovation atmosphere, TFL is rather more helpful [Xie et al., 2018]. The scholars also pinpointed the mediators between TFL and innovation. While TFL boosts innovation via individual identification and building trust, in TAL trust plays no role. Thus, under the guidance of a transactional leader innovative autonomy is promoted but employees cannot perceive shared goals and visions [Xie et al., 2018].

In 2018 such aspect as creativity was under a scrutiny. It was established in one study that TFL is positively connected with creativity through a situational promotion focus [Kark et al., 2018]. However, TAL affects creativity negatively as it is aligned with situational prevention focus. Similar results in terms of regulatory focus can be observed in other studies. Delegach et al. [Delegach et al., 2017] also attribute TFL to promotion focus and TAL to prevention focus. According to [Johnson et al., 2017], the components of TAL should be considered differently: management by exception is linked to prevention focus while contingent reward is linked to both foci. Lai et al. [Lai, Hsu, Li, 2018] also investigated the correlation between regulatory focus and the leadership styles by exploring the dimensions of the concepts. The authors further revealed that inspiration, idealized influence and intelligent stimulation lead to promotion focus (teams become promotion-oriented), whereas management by exception leads to prevention focus (teams become prevention-oriented). It is interesting that individualized consideration was found to have no effect on forming promotion focus.

With regard to safety, it is stated that TFL has a stronger influence on it [Clarke, Taylor, 2018]. The authors conclude that TFL is associated with safety participation while TAL encourages safety compliance. Another informative study of this year focused on the difference in perceptions of leadership style among followers and their leader [Vignoli et al., 2018]. It was proposed that if a leader uses TFL but is perceived by their employees differently, it may have a negative impact on employees’ outcomes. However, in terms of TAL the disagreement was of no effect.

The year 2018 encompasses some research papers that investigated sales industry. One study revealed that TAL moderates positively the link between word-of-mouth, customer satisfaction and salespeople’s self-efficacy [Vieira, Perin, Sampaio, 2018]. However, TFL is claimed to reduce the positive effects of self-efficacy. It is pointed out that under TFL salespeople may become dependent on support and guidance and thus struggle to make their own decisions and proceed with work. Furthermore, another paper concluded that central salespeople with low role-commitment may severely undermine the effect of a transformational manager on other employees [Hayati, Atefi, Ahearne, 2018]. As TFL focuses on internal motivation, the leader’s goals and perspectives may be contradicted and opposed. Nevertheless, since TAL works through compliance, the impact of low-committed central salespeople is lessened.

Year 2019. The final year of this research is considered to have a number of papers that have investigated new areas and explored the notions of leadership styles from a different perspective. In 2019 studies devoted to leadership training have become more popular [An et al., 2019]. The study [Jensen, Andersen, Jacobsen, 2019] moved past the assumption that TFL is always beneficial. As the authors demonstrate, the negative side of leadership is present: in case the values of employees are incongruent with the values of a company, the use of leadership may affect employee motivation negatively. The authors conclude that since TFL is related to the creation of a vision, it will be of a more negative impact than TAL.

Another study dedicated to higher education revealed that such component of TAL as management by exception can be also advantageous [Torlak, Kuzey, 2019]. It is proposed in the article that management by exception, as well as all the dimensions of TFL, is positively related to employee job performance and employee job satisfaction. In contrast, no association of contingent rewards with these aspects was found. This is partially consistent with the previous study that highlighted a positive impact of TAL on job performance [Masa’deh et al., 2016]. The paper reinforces the idea of investigating the concepts of leadership styles by measuring the effects of their components. The same approach has already been noticed in the previous research [Hoffmann 2016; Lai, Hsu, Li, 2018; Liu, Chan, 2017]. The scholars of the article further stress the necessity of both leadership styles in education, with the remark that the starting point is to be with TAL and once efficiency is achieved, TFL can be introduced [Torlak, Kuzey, 2019]. The suggestion that TFL should be employed at a later stage has already been made by some other researchers [Zheng, Wu, Xie, 2017].

With regard to safety in the workplace, the study of 2019 puts forward the idea of a negative correlation between TAL and safety outcomes [Molnar et al., 2019]. In line with the previous study [Von Thiele Schwarz, Hasson, Tafvelin, 2016], it is said that TAL, especially management by exception active, may increase minor injuries and lead to fewer safety initiatives. Moreover, no effect of TFL on safety was found. It contradicts the previous research which confirmed the positive effect of both leadership styles on safety outcomes [Grill et al., 2017]. The authors posit that in order to promote safety environment, it is essential to employ safety-specific leadership and constantly communicate safety and serve as a role model [Molnar et al., 2019].

The studies devoted to supply chain highlight the importance of both styles. Birasnav and Bienstock [Birasnav, Bienstock, 2019] postulate that TFL is beneficial in terms of integration with external supply chain partners, whereas TAL is positively associated with internal integration within manufacturing companies. Another research paper points out that the role of TAL should not be neglected by scholars and practitioners [Mokhtar, Genovese, 2019]. The findings indicate that both TFL and TAL contribute to reverse supply chain performance through such mediators as trust and power respectively.

A number of research studies pinpointed that TFL can be more advantageous than TAL. It was revealed that it has a positive impact on employees’ behavioral intention towards information security [Guhr, Lebek, Breitner, 2019]. However, no influence of TAL was detected. Furthermore, TFL was found to have a positive effect on promoting work engagement and retaining human capital [Lee et al., 2019]. The authors propose that the mediators between TFL and these factors are supervisory coaching and performance feedback which are absent in TAL.

Partially in accordance with the previous research [Hu et al., 2016], the study of this year confirmed the positive effect of combining the two leadership styles in healthcare [Fletcher et al., 2019]. The authors of another study also stressed “a positive synergy effect beyond the combined effect of both leadership behaviors” [Cho et al., 2019, p. 19]. Moreover, the research paper was informative in that it shed light on the importance of cross-national context while measuring the effectiveness of leadership styles. The study thus revealed that TAL is positively related to affective organizational commitment only for Korean employees, whereas the effect of it on the U.S. employees was not found [Cho et al., 2019].

Outline. The analysis of the last four years allowed us to pinpoint some general trends and thus contribute to the research on TFL and TAL. Supply chain and healthcare were found to be the most popular areas among the research articles. With regard to organizational outcomes, a significant number of papers studied innovation, safety and organizational commitment.

The approach to TAL has changed in comparison with that of the founders. Bass [Bass, 1985; 1990] considered neither a negative impact of TFL nor a positive side of TAL in his research. However, academic papers of the last four years explored these gaps and provided evidence of the positive and negative effects of both styles (e.g. [Jensen, Andersen, Jacobsen, 2019; Mokhtar et al., 2019; Molnar et al., 2019]). The relationship between TFL and TAL has also been reconsidered. Burns [Burns, 1978] attributed the terms to the opposite ends of a continuum, implying that a leader can use either TFL or TAL. However, today the idea of combining the two styles is popular among researchers. It suggests that TFL and TAL are not the opposite notions but rather synergetic and complement each other and thus they may be both beneficial under certain factors [Baškarada, Watson, Cromaty, 2016; Guhr, Lebek, Breitner, 2019]. Hence, a balanced approach to TFL and TAL has come in the spotlight [Shao, Feng, Hu, 2016; Xie et al., 2018]. It implies that while both TFL and TAL are integrated in one leader, one style dominates the other depending on a situation [Jensen et al., 2019]. It is essential to take into consideration that due to nonmaterialistic incentives of TFL, which are considered to be more complex than the system of rewards in TAL, this leadership style is on more shaky ground and may be easily affected [Hayati, Atefi, Ahearne, 2018].

The analysis of the research papers in the last four years enabled us to pinpoint the cases in which a particular style may be of a more benefit. TFL functions well for external integration, work engagement, innovation, creativity and employees’ entrepreneurial behavior. However, TFL may have negative implications in case of value incongruence between employees and an organization, if the number of low-committed central employees is high or if employees perceive the style of their manager differently. In these cases the presence of TAL was found to have a marginal impact and thus recommended. TAL may be of a more benefit to internal integration, knowledge sharing, salespeople’s self-efficacy, under limited resources and time or when the number of low-committed central employees is high.

In the research papers of 2016–2019 a switch from regarding TFL and TAL as homogeneous concepts to investigating their components in more detail is noticeable. Many scholars avoid drawing conclusions about the effects of TFL and TAL as a whole. They prefer outlining the impact of each component separately [Hoffmann, 2016; Molnar et al. 2019; Torlak, Kuzey, 2019]. This premise is in line with the previous research [Deinert et al., 2015] which demonstrated that the components within the same leadership style may have a diverse effect.

The research on laissez-faire as leadership style has decreased over the last years. As Bass [Bass, 1985] proposed, a laissez-faire leader avoids taking responsibilities and making decisions. Since many research papers have shown that laissez-faire is negatively related to organizational outcomes, researchers do not always include it in their study (e.g. [Molnar et al., 2019]). Among the research articles investigated, three papers from 2016 and 2017 measured laissez-faire as well as TFL and TAL, whereas in 2019 only one paper considered laissez-faire in its metrics.

According to the studies of 2016–2019, in some spheres a scarcity of data is present and therefore further scrutiny is required. First, the effect of leadership styles on leaders themselves has not been studied properly. Only one research was found to investigate this aspect [Lanaj, Johnson, Lee, 2016]. The findings of this study support the assumptions of Bass and Riggio [Bass, Rigio, 2006] who acknowledged a leader’s development through TFL. However, more research is required as the findings may stimulate managers to adopt leadership styles. Second, it is crucial to pay attention to the MLQ and the way it measures TAL. As suggested, the MLQ may underestimate the value of TAL and its components [Clarke, 2013; Molnar et al., 2019]. It may explain the fact why most studies focused mainly on TFL and considered it more effective.

 

LIMITATIONS AND FUTURE RESEARCH

This study has potential limitations that are worth noting. First, only Scopus as a database for article selection was considered. Second, the selection of articles was based on three indicators such as journal metrics, article metrics, author metrics. However, other factors that scholars take into consideration while evaluating the credibility of research exist. Third, as it was noted previously, the information on the metrics was obtained on the 25^th of June. Since the figures of these indicators may change frequently, especially articles’ citation index, other papers could have been selected on a different day. Finally, despite the fact the advanced search and the developed command on Scopus were employed, a number of articles devoted to TFL and TAL might have been absent in the results of the platform. Researchers have ample room for improvements in future studies. Forthcoming research should also focus on other leadership styles: within the rapidly changing work conditions, research focusing on E-leadership will become more and more topical [Contreras et al., 2020; Müller & Niessen, 2019].

 

CONCLUSION

The above study has attempted to provide an overview of the tendencies in the research of TFL and TAL in the last four years. It was based on literature review and integrated different research papers from Scopus according to a particular method. The results of the present study contribute to an increased understanding of the notions of TFL and TAL and how they affect employees and different organizational outcomes. The main findings indicate that the perception of TFL and TAL has changed in comparison to the views of the founders. TFL and TAL are not regarded as the opposite leadership styles but rather as synergetic and contingent on various factors. This highlights the importance of being able to identify a situation and switch between the two styles accordingly. Moreover, due to nonmaterialistic incentives of TFL, the effects of it may become negative under certain conditions which do not influence the effects of TAL. Thus, some researchers consider TAL to be a more stable leadership style and suggest implementing it at initial stages of a project, whereas TFL may be introduced later. The findings also show that TFL and TAL are to be studied by examining their dimensions since the components within one style may influence differently.

The study reveals the gaps in the research of TFL and TAL and recommends areas for future investigation: the influence of leadership styles on leaders, the effects of TFL and TAL in a cross-national context, the revision of the measurement of TAL in MLQ. Further studies may be also carried out to investigate some organizational outcomes in which the results of the research papers were controversial: safety, innovation, knowledge sharing, etc.

1. Afsar B., Badir Y. F., Saeed B. B., Hafeez S. Transformational and transactional leadership and employee’s entrepreneurial behavior in knowledge-intensive industries. International Journal of Human Resource Management 2017. 28 (2): 307-332.

2. Aksnes D. W., Sivertsen G. A criteria-based assessment of the coverage of Scopus and Web of Science. Journal of Data and information Science. 2019. 4 (1): 1-21.

3. Al-Husseini S., Elbeltagi I. Transformational leadership and innovation: A comparison study between Iraq’s public and private higher education. Studies in Higher Education 41 2016. (1): 159-181.

4. An S.-H., Meier K. J., Bøllingtoft A., Andersen L. B. Employee perceived effect of leadership training: Comparing public and private organizations. International Public Management Journal. 2019. 22 (1): 2-28.

5. Asiri S. A., Rohrer W. W., Al-Surimi K., Da’ar O. O., Ahmed A. The association of leadership styles and empowerment with nurses' organizational commitment in an acute health care setting: A cross-sectional study. BMC Nursing. 2016. 15 (1) 124-145.

6. Avolio, B.J., & Bass, B.M. Transformational leadership, charisma, and beyond. In J.G. Hunt, B.R. Baliga, H.P. Dachler, & C.A. Schriesheim (Eds.), 1988.

7. Emerging leadership vistas (pp. 2949). Lexington, MA: Lexington Books.

8. Avolio B. J., Bass B. M. Multifactor Leadership Questionnaire. Manual and Sampler Set. 2004. 3rd ed. Redwood City, CA: Mind Garden.

9. Avolio B. J., Bass B. M., Jung D. I. Re-examining the components of transformational and transactional leadership using the multifactor leadership questionnaire. Journal of Occupational and Organizational Psychology. 1999. 72 (4): 441-462.

10. Avolio, B. Full Leadership Development: Building the Vital Forces in Organization. Thousand Oaks: Sage Publications. 1999.

11. Aydin A., Sarier Y., Uysal S. The effect of school principals’ leadership styles on teachers’ organizational commitment and job satisfaction. Kuram ve Uygulamada Egitim Bilimleri. 2013. 13 (2): 806-811.

12. Ball R., Tunger D. Science indicators revisited - Science citation index versus SCOPUS: A bibliometric comparison of both citation databases. Information Services and Use. 2006. 26 (4): 293-301.

13. Baškarada S., Watson J., Cromaty J. Leadership and organizational ambidexterity. Journal of Management Development. 2016. 35 (6): 778-788.

14. Bass, B.M. Stogdill’s handbook of leadership (rev. ed.). New York: Free Press. 1981.

15. Bass B. M. Leadership and Performance Beyond Expectations. NY: Free Press. 1985.

16. Bass B. M. From transactional to transformational leadership: Learning to share the vision. Organizational Dynamics. 1990. 18 (3): 19-31.

17. Bass, B. M. Theory of transformational leadership redux. Leadership Quarterly. 1995. 6 (4): 463-478

18. Bass, B. M. Transformational leadership: Industry, military, and educational impact. Mahwah, NJ: Erlbaum. 1998.

19. Bass, B. M. Two decades of research and development in transformational leadership. European Journal of Work and Organizational Psychology, 1999. 8 (1): 9-32.

20. Bass, B.M., Avolio, B.J., & Goodheim, L. Biography and the assessment of transformational leadership at the world class level. Journal of Management, 1987. 13 (1) :7-19.

21. Bass B. M., Avolio B. J. (Eds.) Improving Organizational Effectiveness through Transformational Leadership. Thousand Oaks, CA: Sage Publications. 1994.

22. Bass B. M., Avolio B. J. Manual for the Multifactor Leadership Questionnaire: Rater Form (5X Short). Palo Alto, CA: Mind Garden. 1995.

23. Bass B. M., Riggio R. E. Transformational leadership. 2nd ed. Mahwah, NJ: Lawrence Erlbaum. 2006.

24. Bass, B.M., Waldman, D.A., Avolio, B.J., & Bebb, M. Transformational leadership and the falling dominoes effect. Group and Organization Studies, 12 (1) :73-87. 1987.

25. Bennis, W., & Nanus, B. Leaders: The strategies for taking charge. New York: Harper & Row. 1985.

26. Birasnav M., Mittal R., Loughlin S. Linking leadership behaviors and information exchange to improve supply chain performance: A conceptual model. Global Journal of Flexible Systems Management. 2015. 16 (2): 205-217.

27. Birasnav M., Bienstock J. Supply chain integration, advanced manufacturing technology, and strategic leadership: An empirical study. Computers and Industrial Engineering. 2019. 130: 142-157.

28. Boal, K.B., & Bryson, J.M. Charismatic leadership: A phenomenological and structural approach. In J.G. Hunt, B.R. Baliga, H.P. Dachler, & CA. Schriesheim (Eds.), Emerging Leadership Vistas (pp. 5-28). Lexington, MA: Lexington Books. 1988.

29. Boamah, Sheila & Laschinger, Heather & Wong, Carol & Clarke, Sean. Effect of transformational leadership on job satisfaction and patient safety outcomes. Nursing Outlook. 2017. 66(2): 180-189.

30. Borgman C. L., Furner J. Scholarly communication and bibliometrics. Annual Review of Information Science and Technology. 2002.36 (1): 3-72.

31. Bronkhorst, B., Steijn, B., & Vermeeren, B. Transformational Leadership, Goal Setting, and Work Motivation: The Case of a Dutch Municipality. Review of Public Personnel Administration, 2015. 35(2): 124-145.

32. Bronkhorst, Babette & Steijn, Bram & Vermeeren, Brenda. Transformational Leadership, Goal Setting, and Work Motivation: The Case of a Dutch Municipality. Review of Public Personnel Administration. 2013.

33. Buil I., Martinez E., Matute J. Transformational leadership and employee performance: The role of identification, engagement and proactive personality. International Journal of Hospitality Management 2019. 77 (5): 64-75.

34. Burns J. M. Leadership. NY: Harper & Row. 1978.

35. Chang W. L., Lee C. Y. Virtual team e-leadership: The effects of leadership style and conflict management mode on the online learning performance of students in a business-planning course. British Journal of Educational Technology. 2013. 44 (6): 986-999.

36. Cho Y., Shin M., Billing T. K., Bhagat R. S. Transformational leadership, transactional leadership, and affective organizational commitment: A closer look at their relationships in two distinct national contexts. Asian Business and Management (article in press). 2019.

37. Clarke S. Safety leadership: A meta-analytic review of transformational and transactional leadership styles as antecedents of safety behaviours. Journal of Occupational and Organizational Psychology. 2013. 86 (1): 22-49.

38. Clarke S., Taylor I. Reducing workplace accidents through the use of leadership interventions: A quasi-experimental field study. Accident Analysis and Prevention. 2018. 121 (12): 314-320.

39. Conger, J.A., & Kanungo, R.N. Toward a behavioral theory of charismatic leadership in organizational settings. Academy of Management Review, 1987. 12 (4), 637-647.

40. Contreras, F., Baykal, E., & Abid, G. E-leadership and teleworking in times of COVID-19 and beyond: What we know and where do we go. Frontiers in Psychology, 2020. 11, 3484.

41. De Groote S. L., Raszewski R. Coverage of Google Scholar, Scopus, and Web of Science: A case study of the h-index in nursing. Nursing Outlook 2012. 60 (6): 391-400.

42. Deinert A., Homan A.C., Boer D., Voelpel S. C., Gutermann D. Transformational leadership sub-dimensions and their link to leaders' personality and performance. The Leadership Quarterly 2015. 26 (6): 1095-1120.

43. Delegach M., Kark R., Katz-Navon T., Van Dijk D. A focus on commitment: the roles of transformational and transactional leadership and self-regulatory focus in fostering organizational and safety commitment. European Journal of Work and Organizational Psychology 2017. 26 (5): 724-740.

44. Doucet O., Poitras J., Chênevert D. The impacts of leadership on workplace conflicts. International Journal of Conflict Management. 2009. 20 (4): 340-354.

45. Dussault M., Frenette E. Supervisors’ transformational leadership and bullying in the workplace. Psychological Reports. 2015. 117 (3): 724-733.

46. Dussault M., Valois P., Frenette É. Validation de l’échelle de Leadership Transformatif du directeur d’école [Transformational leadership of school principals: validation of a scale]. Psychologie du Travail et des Organisations [Psychology of Work and Organizations] 2007.13 (2): 37-52.

47. Epitropaki O., Martin R.,From Ideal to Real: A Longitudinal Study of the Role of Implicit Leadership Theories on Leader-Member Exchanges and Employee Outcomes. Journal of Applied Psychology, 2005. 90 (4): 659-676

48. Fletcher K., Friedman A., Piedimonte G. Transformational and transactional leadership in healthcare seen through the lens of pediatrics. Journal of Pediatrics. 2019. 204 (1): 7-9.

49. Grill M., Pousette A., Nielsen K., Grytnes R., Tcrner M. Safety leadership at construction sites: The importance of rule-oriented and participative leadership. Scandinavian Journal of Work, Environment and Health. 2017. 43 (4): 375-384.

50. Grisaffe D. B., Vanmeter R., Chonko L. B. Serving first for the benefit of others: Preliminary evidence for a hierarchical conceptualization of servant leadership. Journal of Personal Selling and Sales Management. 2016. 36 (1): 40-58.

51. Gong, Yaping & Huang, Jia-Chi & Farh, Jiing-Lih. Employee Learning Orientation, Transformational Leadership, and Employee Creativity: The Mediating Role of Employee Creative Self-Efficacy. Academy of Management Journal. 2009. 52(4): 765-778.

52. Guhr N., Lebek B., Breitner M. H. The impact of leadership on employees' intended information security behaviour: An examination of the full-range leadership theory. Information Systems Journal. 2019. 29 (2): 340-362.

53. Harzing A.-W. Citation analysis across disciplines: The impact of different data sources and citation metrics. URL: https://harzing.com/publications/white-papers/citation-analysis-across-disciplines. 2010. (accessed: 29.06.2019).

54. Hayati B., Atefi Y., Ahearne M. Sales force leadership during strategy implementation: a social network perspective. Journal of the Academy of Marketing Science. 2018. 46 (4): 612-631.

55. Herrmann D., Felfe J. Moderators of the relationship between leadership style and employee creativity: The role of task novelty and personal initiative. Creativity Research Journal. 2013. 25 (2): 172-181.

56. Hoffmann M.D. Investigating athlete mentoring functions and their association with leadership behaviours and protégé satisfaction. International Journal of Sport and Exercise Psychology. 2016.14 (1): 85-102.

57. House, R.J. A path goal theory of leader effectiveness. Administrative Science Quarterly, 1971. 16 (3): 321-338.

58. House, R.J. A 1976 theory of charismatic leadership. In J.G. Hunt & L.L. Larson (Eds.), Leadership: The cutting edge. Carbondale, IL: Southern Illinois University Press. 1977.

59. House, R.J. Leadership research: Some forgotten, ignored, or overlooked findings. In J.G. Hunt, B.R. Baliga, H.P. Dachler, & C.A. Schriesheim (Eds.), Emerging leadership vistas. Lexington, MA: Lexington. 1988.

60. House, R.J., & Baetz, M.L. Leadership: Some empirical generalizations and new research directions. In B.M. Staw (Ed.), Research in Organizational Behavior, 1979. 1: 341-423

61. House R.J., Woycke J. & Fodor E.M. Perceived behavior and effectiveness of charismatic and non-charismatic U.S. presidents. In Conger, J. & Kanungo, R. (Eds.), Charismatic Leadership and Management. San Francisco: Jossey- Bass. 1988.

62. House R.J., Spangler W.D. & Woycke J. Personality and charisma in the U.S. presidency: A psychological theory of leadership effectiveness. Working paper, Wharton Business School, University of Pennsylvania. 1989.

63. Howell J.M., & Frost P.J. A laboratory study of charismatic leadership. Organizational Behavior and Human Decision Processes, 43 (2), 243-269. 1989.

64. Howell J.M. & Avolio B.J. Transformational leadership, transactional leadership, locus of control, and support for innovation: Key predictors of consolidated business-unit performance. Journal of Applied Psychology, 1993. 78 (6), 891-902

65. Hu Y.-Y., Parker S.H., Lipsitz S.R., Arriaga A.F., Peyre S.E., Corso K.A., Roth E.M., Yule S.J., Greenberg C.C. Surgeons’ leadership styles and team behavior in the operating room. Journal of the American College of Surgeons. 2016. 222 (1): 41-51.

66. Jensen U.T., Andersen L.B., Jacobsen C.B. Only when we agree! How value congruence moderates the impact of goal-oriented leadership on public service motivation. Public Administration Review 2019. 79 (1): 12-24.

67. Jia X., Chen J., Mei L., Wu Q. How leadership matters in organizational innovation: A perspective of openness. Management Decision. 2018. 56 (1): 6-25.

68. Johnson R.E., King D.D., Joanna Lin S.-H., Jackson Walker E.M., Wang M. Regulatory focus trickle-down: How leader regulatory focus and behavior shape follower regulatory focus. Organizational Behavior and Human Decision Processes. 2017.140 (1): 29-45.

69. Judge T.A., Piccolo R.F. Transformational and Transactional Leadership: A Meta-Analytic Test of Their Relative Validity. Journal of Applied Psychology, 2004. 89 (5): 755-768

70. Kark R., Van Dijk D., Vashdi D.R. Motivated or demotivated to be creative: The role of self-regulatory focus in transformational and transactional leadership processes. Applied Psychology, 2018. 67 (1): 186-224.

71. Kelly S., MacDonald P. A look at leadership styles and workplace solidarity communication. International Journal of Business Communication 2019. 56 (3): 432-448.

72. Kim J.-G., Lee S.-Y. Effects of transformational and transactional leadership on employees’ creative behaviour: Mediating effects of work motivation and job satisfaction. Asian Journal of Technology Innovation 2011.19 (2): 233-247.

73. Lai C.-Y., Hsu J. S.-C., Li Y. Leadership, regulatory focus and information systems development project team performance. International Journal of Project Management. 2018. 36 (3): 566-582.

74. Lanaj K., Johnson R. E., Lee S. M. Benefits of transformational behaviors for leaders: A daily investigation of leader behaviors and need fulfillment. Journal of Applied Psychology. 2016. 101 (2): 237-251.

75. Lee M.C.C., Idris M.A., Tuckey M. Supervisory coaching and performance feedback as mediators of the relationships between leadership styles, work engagement, and turnover intention, Human Resource Development International. 2019. 22 (3): 257-282.

76. LePine M., Zhang Y., Crawford E.R. & Rich B.L. Turning their pain to gain: Charismatic leader influence on follower stress appraisal and job performance. Academy of Management Journal, 2016. 59 (3): 1036-1059.

77. Lewin K., Lippitt R., White R. K. Patterns of aggressive behavior in experimentally created “social climates”. Journal of Social Psychology. 1939. 10 (5): 279-299.

78. Lin C.-S., Huang P.-C., Chen S.-J., Huang L.-C. Pseudotransformational leadership is in the eyes of the subordinates. Journal of Business Ethics. 2017. 141 (1): 179-190.

79. Lipponen J., Bardi A., Haapamaki J. The interaction between values and organizational identification in predicting suggestion-making at work. Journal of Occupational and Organizational Psychology. 2008. 81 (2): 241-248.

80. Liu A.M. M., Chan I.Y.S. Understanding the interplay of organizational climate and leadership in construction innovation. Journal of Management in Engineering. 2017. 33 (5). 1-22.

81. Masa’deh R., Obeidat B.Y., Tarhini A. A Jordanian empirical study of the associations among transformational leadership, transactional leadership, knowledge sharing, job performance, and firm performance: A structural equation modelling approach. Journal of Management Development. 2016. 35 (5): 681-705.

82. Mokhtar A. R. M., Genovese A., Brint A., Kumar N. Improving reverse supply chain performance: The role of supply chain leadership and governance mechanisms. Journal of Cleaner Production. 2019. 216 (4): 42-45.

83. Molnar M.M., Von Thiele Schwarz U., Hellgren J., Hasson H., Tafvelin S. Leading for safety: A question of leadership focus. Safety and Health at Work. 2019.10 (2): 180-187.

84. Müller T., and Niessen C. Self-leadership in the context of part-time teleworking. Journal of Organizational Behavior. 2019. 40, 883-898.

85. Outhwaite S. The importance of leadership in the development of an integrated team. Journal of Nursing Management. 2003. 11 (6): 371-376.

86. Podsakoff P.M., MacKenzie S.B., Moorman R.H., Fetter R. Transformational Leaders Behaviors And Their Effects On Followers’ Trust In Leader, Satisfaction, And Organizational Citizenship Behaviors. 1990.

87. Prasad B., Junni P. CEO transformational and transactional leadership and organizational innovation: The moderating role of environmental dynamism. Management Decision. 2016. 54 (7): 1542-1568.

88. Rezvani A., Khosravi P., Dong L. Motivating users toward continued usage of information systems: Self-determination theory perspective. Computers in Human Behavior. 2017. 76: 263-275.

89. Rowold J. Transformational and transactional leadership in martial arts. Journal of Applied Sport Psychology. 2006. 18 (4): 312-325.

90. Shamir B., House R.J. & Arthur M.B. The transformational effects of charismatic leadership: A motivational theory. Unpublished Working Paper, The Hebrew University, Jerusalem. 1988.

91. Shao Z., Feng Y., Hu Q. Effectiveness of top management support in enterprise systems success: A contingency perspective of fit between leadership style and system life-cycle. European Journal of Information Systems. 2016. 25 (2): 131-153.

92. Shao Z., Feng Y., Hu Q. Impact of top management leadership styles on ERP assimilation and the role of organizational learning. Information and Management. 2017. 54 (7): 902-919.

93. Seltzer J. & Bass B.M. Transformational leadership: Beyond initiation and consideration. Journal of Management, 1990. 16 (4): 693-703.

94. Stock R.M., Zacharias N.A., Schnellbaecher A. How do strategy and leadership styles jointly affect co-development and its innovation outcomes? Journal of Product Innovation Management. 2017. 34 (2): 201-222.

95. Stogdill, R.M. Handbook of leadership. New York: Free Press. 1974.

96. Tafvelin S., Hyvönen U., Westerberg K. Transformational leadership in the social work context: The importance of leader continuity and co-worker support. British Journal of Social Work. 2014. 44 (4): 886-904.

97. Teoman S., Ulengin F. The impact of management leadership on quality performance throughout a supply chain: An empirical study. Total Quality Management and Business Excellence. 2018. 19 (11-12): 1427-1451.

98. Tichy N. & DeVanna M. The transformational leader. New York: Wiley. 1986.

99. Torlak N.G., Kuzey C. Leadership, job satisfaction and performance links in private education institutes of Pakistan. International Journal of Productivity and Performance Management. 2019. 68 (2): 276-295.

100. Van Jaarsveld L., Mentz P.J., Ellis S. Implementing the Multifactor Leadership Questionnaire (MLQ) in a challenging context: Results from a large-scale quantitative study. International Journal of Educational Management. 2019. 33 (4): 604-613.

101. Van Knippenberg D., Sitkin S.B. A critical assessment of charismatic - transformational leadership research: Back to the drawing board? Academy of Management Annals. 2013. 7 (1): 1-60.

102. Van Raan A.F.J. Advanced bibliometric methods as quantitative core of peer-review based evaluation and foresight exercises. Scientometrics. 1996. 36 (3): 397-420.

103. Vasilagos Tryfon & Polychroniou Panagiotis & Maroudas Leonidas. Relationship Between Supervisor’s Emotional Intelligence and Transformational Leadership in Hotel Organizations. 2017. 91-95.

104. Vieira V.A., Perin M.G., Sampaio C.H. The moderating effect of managers’ leadership behavior on salespeople’s self-efficacy. Journal of Retailing and Consumer Services. 2018. 40: 150-162.

105. Vignoli M., Depolo M., Cifuentes M., Punnett L. Disagreements on leadership styles between supervisors and employees are related to employees’ well-being and work team outcomes. International Journal of Workplace Health Management 2018. 11 (5): 274-293.

106. Von Thiele Schwarz U., Hasson H., Tafvelin S. Leadership training as an occupational health intervention: Improved safety and sustained productivity. Safety Science. 2016. 81 (1): 35-45.

107. Willis S., Clarke S., O’Connor E. Contextualizing leadership: Transformational leadership and management-byexception- active in safety-critical contexts. Journal of Occupational and Organizational Psychology. 2017. 90 (3): 281-305.

108. Xie L. Leadership and organizational learning culture: A systematic literature review. European Journal of Training and Development. 2019. 43 (1-2): 76-104.

109. Xie Y., Xue W., Li L., Wang A., Chen Y., Zheng Q. Leadership style and innovation atmosphere in enterprises: An empirical study. Technological Forecasting and Social Change. 2018. 135 (5): 257-265.

110. Yahaya R., Ebrahim F. Leadership styles and organizational commitment: Literature review. Journal of Management Development. 2016. 35 (2): 190-216.

111. Yukl G.A. Managerial leadership: A review of theory and research. Yearly Review of Management, IS, 1989. 251- 289.

112. Yukl G. Leadership in Organizations. Upple Saddle River, NJ: Prentice Hall. 2002.

113. Zehnder C., Herz H., Bonardi J.-P. A productive clash of cultures: Injecting economics into leadership research. Leadership Quarterly. 2017. 28 (1): 65-85.

114. Zhang L., Cao T., Wang Y. The mediation role of leadership styles in integrated project collaboration: An emotional intelligence perspective. International Journal of Project Management. 2018. 36 (2): 317-330.

115. Zheng J., Wu G., Xie H. Impacts of leadership on projectbased organizational innovation performance: The mediator of knowledge sharing and moderator of social capital. Sustainability. 2017. 9 (10), 1893: 1-22.