How transformational leadership influences employees’ job-related outcomes through public service motivation: Does power distance orientation matter?

Abstract The goal of this research is to examine the influence of transformational leadership (TL) on employees’ job-related outcomes, noting the mediating roles of public service motivation (PSM) as well as the moderating effect of power distance orientation (PDO). Surveys were collected from 605 civil servants currently working in local governments in Vietnam and the researcher used the partial least squares structural equation modeling (PLS-SEM) technique with SmartPLS 3.0 software to test hypotheses. The findings showed that there was a positive influence of transformational leadership on employees’ work outcomes; this relationship was mediated partially through public service motivation. Also, the finding revealed the moderating effects of power distance orientation on the effect of perceived transformational leadership on public service motivation, job satisfaction, and job performance. Civil servants with high power distance orientation tended to dampen the positive relationship between transformational leadership and public service motivation which led to decreased job satisfaction and job performance. Based on the findings, it is recommended that managers or leaders in Vietnamese local governments should apply transformational leadership in practice to improve the level of employee work outcomes. Finally, this study broadens new knowledge to the existing literature on transformational leadership and job-related outcomes by proposing an alternative model of how this relationship exists. Besides, the findings showed that although transformational leaders can lead to good behavioral outcomes, high power distance orientation could mitigate this benefit.


Introduction
The appealing idea of a motivated workforce has been a great locus of scholarly interest irrespective of the sector in which analyses are made (Chehab et al., 2022). However, the majority of the existing literature on motivation has emphasized on motivating staffs in the private sector (Min et al., 2021). For the public sector, motivation is recognized as one of the three big issues related to public management, alongside micromanagement and measurement (Perry, 2021). Motivation is seen as a tool for eliciting a number of desirable and positive individual and organizational outcomes (Vuong, 2022b).
In recent decades, New Public Management (NPM) has emerged as a motivational construct for energizing a perceived lackadaisical bureaucracy. NPM and its underlying presumptions are closely related to principal-agent and self-interest-based thinking (Perry et al., 2009). As an alternative to the more cynical assumptions of bureaucracy proposed by NPM, public service motivation (PSM) has been viewed as a viable assessment for explaining public service and has garnered a considerable amount of scholarly attention (Perry, 2021). The PSM perspective postulates distinct motives associated with public service and implies "beliefs, values, and attitudes that go beyond self-interest and organizational interest that concern the interest of a larger political entity" (Perry & Wise, 1990). PSM is a likely focus of attention, given its values of public service, political activity, and concern for others-oriented values that directly challenge the NPM approach. Furthermore, recent failures in the corporate world in responding to the global economic crises suggest that private sector know-how is not the only means for improving public sector productivity. PSM offers an alternative approach as a lever for realizing the basic functions of human resources management (HRM) such as attraction, selection, retention, training, and a number of organizational outcomes. Consequently, PSM has emerged as one of the more consistent alternative paradigms to NPM.
Study on the concept of PSM has dramatically spiked in the last decade, and it can now be categorized as internationalized, multidisciplinary, and multi-sectoral (Hameduddin & Engbers, 2022). The most comprehensive theoretical frame in order to understand the patterns and antecedent factors of PSM, developed by Perry (2000), identified three blocks of variables corresponding to three distinct contexts in which PSM is shaped. While socio-historical context included socialization processes that occur outside of the organizations, motivational context referred to a group of organizational factors such as job characteristics, organizational incentives, and work environment. The third block of this model indicated personal attributes. Interestingly, there are only some scholars who have conducted theoretical or empirical investigations of the origins of PSM (Hameduddin & Engbers, 2022). Furthermore, few of these studies specifically incorporated transformational leadership in their model as a key issue for the future of government organizations (Kim et al., 2021). Nowadays, local governments must learn to do more with fewer human resources and less money. The challenge faced by public administrators is how to maintain productivity in the face of current financial challenges and to continue addressing future issues of job satisfaction, engagement, and performance. Therefore, transformational leadership may be one of the good variables to address this issue for governmental organizations. Transformational leadership is defined as leadership behavior that inspires and motivates subordinates to perform beyond expectations in pursuit of organizational goals (Wright et al., 2012). This style of leadership is actively involved in achieving objectives and allows the leader to involve their subordinates in the problem-solving process while aiding their growth and development within the organization. Currently, there has been little focus on the mechanisms through which a transformational leader impacts his/her followers' public service motivation and job-related outcomes (Saira et al., 2021;Vuong, 2022a). Therefore, scholars are paying more attention to this area to enhance an extra understanding of transformational leadership.
Moreover, while transformational leadership and job-related outcomes (e.g., job satisfaction, employee engagement, and job performance) in public sector employees remain important factors in the performance of these organizations, it is not known if and how these factors relate to PSM. An initial review of the public service motivation literature revealed three findings. First, research studies generally support the existence of PSM in the public sector. Second, transformational leadership and job satisfaction are widely asserted to be related to the high performance of employees. Third, the true relationships between transformational leadership and PSM; PSM and job satisfaction; PSM and employee engagement are not clear since the significance, direction, and strength of these relationships vary across individual studies (Hameduddin & Engbers, 2022). Public service motivation is essential to the success of public sectors; for this reason, it is important that research on these constructs be as thorough and clear as possible. Also, previous research has extensively exanimated the various antecedences and consequences of PSM (e.g., Miao et al., 2019;Riccucci, 2017), however these have been studied mainly in the context of developed countries.
This study will focus on testing the antecedent (e.g., transformational leadership) and consequences (e.g., job satisfaction, employee engagement, and job performance) of the PSM construct in developing countries such as Vietnam. Vietnam is currently experiencing an ongoing transition and change period with regard to its deep-rooted civil service system that reflects its centralist and statist tradition. Politicians are strongly calling for a drastic shift toward a more business-like management approach in the Vietnamese public sector. This research will beneficially expand the scope of international study by adding new knowledge about the motivation of civil servants who have experienced drastic economic and political changes in their lives. Therefore, introducing the PSM construct to the contexts of countries like Vietnam-a country at a relatively nascent stage of reform-could prove interesting and fruitful.
In addition, this study is a new attempt to apply Vietnamese cultural value orientation (e.g., power distance orientation) to the association between transformational leadership and behavioral outcomes (e.g., public service motivation, job satisfaction, engagement, and performance). (Hofstede, 2001) stated that power distance is "the extent to which an individual accepts the unequal distribution of power in institutions and organizations". Power distance orientation (PDO) identifies an individual-level construct in cultural values relating to status, beliefs, authority, and hierarchy within the organization (Wei et al., 2017). As power distance orientation reflects individual employees' opinions regarding their beliefs, leadership styles, and status in the organization, the communication style of their immediate supervisors may hinder a trustful leader-follower relationship if there is a gap in perceived power distance orientation (Auh et al., 2016). PDO has been widely employed in the study to explore the effects on employee behaviors, leadership, and organizational outcomes (e.g., Xenikou, 2017). Ergeneli et al. (2007) specified that individuals' PDO can vary by culture. Kirkman et al. (2009) also stated that how a leader's behaviors interact with followers' PDO can impact employees' mindset, attitudes, and behaviors. However, there has been no study on how cultural values (e.g., power distance orientation) in public organizations change the relationship between transformational leadership and behavioral outcomes. Thus, this study will explore the potential critical moderator of power distance orientation. It will clarify the mechanism in the relationship between transformational leadership and employees' behavioral outcomes (e.g., public service motivation, job satisfaction, engagement, and performance) within an Asian, and particularly a Vietnamese context.

Theoretical background
Social cognitive theory (SCT) of Bandura (1986) emphasizes both learning and cognition and was developed primarily as a means of explaining how people learn to behave through several component processes. This theory proposes that humans can learn through observation without the need for imitation-learning can be either direct or indirect (i.e., vicarious).
Social exchange theory (SET) explains that the behavior of the employees is motivated because there is a desire to minimize the negative experiences and maximize the positive experiences through social interactions on the basis of costs and benefits (Blau, 1964). SET explains why the variables within a scenario impact each other in certain ways. SET can also be applied to the organizational relationship where the interactions between the employees and leaders are of a reciprocal nature. Jung and Sosik (2002) defined transformational leadership as "encouraging human development and interaction and promoting collective motivation and outcomes". More than developing contractual leader-follower relationships, transformational leaders motivate and inspire followers to obtain common objectives through relationships (Avolio & Bass, 2004). Avolio and Bass (2004) identified four dimensions of TL such as idealized influence, inspirational motivation, intellectual stimulation, and individual consideration. In particular, idealized influence refers to a transformational leader's ability to act as a role model. Inspirational motivation refers to a transformational leader who has the ability to inspire others. Intellectual stimulation involves a transformational leader who encourages creativity from both followers and self. Individual consideration describes that a transformational leader earns the trust, admiration, and respect of his or her followers by caring for their needs.

Job performance
Today, in the global competitive environment, many organizations have extended measurable job performance level by establishing work standards that include assessing the results and behaviors of employees that contribute to the success of the organization. The job performance of employees has played an important role in leading to the success of an organization (Chen, 2009). JP has been defined this concept as "the overall expected value from employee's behaviors carried out over the course of a set period of time" . Ojo et al. (2018) described that JP as behaviors or actions which are relevant to the goals of an organization.
When employee goals tie to organizational goals, the production toward one equals the achievement of the other. A transformational leader's followers feel trust, admiration, loyalty, and respect for their leader, which leads to the follower's motivation to accept the challenge and push to succeed. Transformational leaders influence followers through vision. They inspire followers with leadership behaviors by leading by example while enhancing the importance of goals. Their actions could lead to a follower's JP. Additionally, according to the SCT theory of Bandura (1986), an employee will learn behaviors from his/her leaders as role models. Transformational leadership is helpful to subordinates' JP because of its motivational characteristics. A transformational leader is observed by employees as a proactive role model due to his/her inspirational motivation and idealized influence. When a follower views his/her leader as a role model, he/she is more likely to trust his/her own abilities and improve confidence to achieve his/her job goals, especially when a leader is more trustworthy and attractive (e.g., a transformational leader). Sürücü et al. (2022) also argued that TL relates positively to JP. Thus, the hypothesis H 1 is proposed: H 1 : Transformational leadership increases civil servants' job performance. Perry and Wise (1990) defined PSM as "an individual's predisposition to respond to motives grounded primarily or uniquely in public institutions or organizations". PSM is also considered as "the beliefs, values, and attitudes that go beyond self-interest and organizational interest, that concern the interest of a larger political entity and that motivate individuals to act accordingly whenever appropriate" (Vandenabeele, 2007). Additionally, along with being committed to the public interest, the presence of both self-sacrifice and compassion leads PSM to motivate civil servants in their activities with others outside of tasks.

Public service motivation
In this flow of leadership perspectives, transformational leadership style has been a popular locus of interest because of its outstanding focus on the leader's ability to stimulate his/her followers cognitive capacity and align personal goals with higher goals of the organizations, and in doing this, consider the needs of individuals in order to achieve the mission of the organization. Wright et al. (2012) argued that TL promotes PSM because transformational leaders communicate and sustain attention on public service-oriented visions. Transformational leaders seek to "elevate the interests of their employees, generate awareness and acceptance of the group mission, and look beyond their own self-interest to the greater good" (Paarlberg & Lavigna, 2010). Hameduddin and Engbers (2022) advocated that transformational leaders could inspire civil servants to "go beyond their immediate self-interest by linking an inspiring vision to their core values". Moreover, empirical support for a positive relationship between TL and PSM was found in some prior studies (e.g., Jensen & Bro, 2018;Wright et al., 2012). Hence, the hypothesis H 2 is posited: H 2 : Transformational leadership positively influences civil servants' public service motivation.
Furthermore, some scholars stated that an individual with higher PSM is more likely to be attracted to employment in a public organization and has higher performance levels. So, if the employers attract a civil servant with high PSM, he/she will have less need for utilitarian rewards to manage performance (Cheng, 2015). They contended that employees with high PSM tend to exert more effort and embrace public duties with high task significance. When civil servants perform meaningful tasks, they follow their convictions and values, which could positively impact individual performance (Miao et al., 2019). Based on the above discussions, the following hypothesis is suggested: H 3 : Public service motivation positively influences civil servants' job performance.

Job satisfaction
Job satisfaction describes "how people feel about their jobs and different aspects of their jobs. It can be interpreted that the happier people feel in their job, the more satisfied they are" (Giao et al., 2020b). JS could be acquired when an employee likes his/her job, or he/she receives positive emotion after appraisal of his/her work.
On the other hand, leadership is also a premise of job satisfaction (Giao et al., 2020a;Kouni et al., 2018;Mureșan et al., 2021). According to Gelfand et al. (2004), building employee trust and developing employees are critical factors in establishing satisfaction with employees. Both of these factors are characteristics of a transformational leader. Baysak and Yener (2015) believed that while working with transformational leaders, followers' trust will develop over time. And with this level of trust, job satisfaction of followers' will increase. Furthermore, through the social contagion processes, the positive moods of transformational leaders influence the followers' moods, resulting in increased follower job satisfaction. Thus, transformational leaders could take advantage of job satisfaction by focusing on the development of employees through individualized consideration. Based on the above-mentioned discussions, the following hypothesis is posited: H 4 : Transformational leadership positively influences civil servants' job satisfaction. Giao et al. (2020b) stated that "it is crucial to study employee's job satisfaction because this thing is considered as an important factor in enhancing job performance as well as organizations' performance and competitiveness". Employees who are satisfied with their job will be inclined to be productive at work. Some studies indicated an expectation that employees with a higher level of satisfaction and experience leads to increased productivity (Akram et al., 2021;Giao et al., 2020b;Vuong et al., 2022a). Based on the social exchange theory of Blau (1964), employees who have gained satisfaction with their work may feel compelled to repay or reciprocate their organization. He advocated that "the most likely form of reciprocation would be high performance, thus completing an exchange sequence which would result in a satisfaction causes performance effect". Based on the above discussion, the following hypothesis is proposed as following: H 5 : Job satisfaction positively influences civil servants' job performance. Camilleri (2007) recognized that issues comprising PSM have created interest because they are regarded as having a positive effect on job satisfaction. Furthermore, Perry et al. (2010) stated that "high PSM is the result of possessing a stronger drive towards the integration of rational, normative, and affective motives into an individual's value set". Therefore, they upheld that for employees to build up their PSM level, they must work in public service because people with PSM hold a set of values connected with contributing to society. Only public organizations reflect values consistent with their own values. When public organizations give sufficient opportunities for civil servants to serve the public interest and provide public good, these public servants could be satisfied with their work. Therefore, the authors argue that the higher PSM for civil servants, the higher the satisfaction level with their jobs. Besides, Min et al. (2021) discovered that PSM had a positive influence on JS. Consequently, the following hypothesis is proposed: H 6 : Public service motivation positively influences civil servants' job satisfaction.

Employee engagement
Employee engagement is defined as "the harnessing of organization members' selves to their work roles; in engagement, people employ and express themselves physically, cognitively, and emotionally during role performances" (Kahn, 1990). In other words, a positive state of mind in a workrelated environment that is characterized by dedication, absorption, and vigor is known as employee engagement. According to the SET theory, civil servants will feel motivated if they realize that their leaders are concerned about their work. When transformational leaders focus on their subordinates by acknowledging and acting on subordinates' requests and considering subordinates' needs for growth and achievement, they could obtain positive leader-follower relationships, which will be beneficial to enhance the sense of belonging to the organization. Civil servants may reciprocate by engaging themselves more in their tasks. So, the author proposes the following hypothesis: H 7 : Transformational leadership positively influences civil servants' employee engagement. Anderfuhren-Biget et al. (2010) stated that PSM is "a personal resource, a form of motivation to perform altruistically to benefit the public". When civil servants perceive correspondence between their values and public organizations' values, they feel useful and valued and are more likely to become engaged. The author states that employees with strong PSM are more willing to serve the public welfare and concentrate on social values and their own intrinsic values, as well as showing the spirit of selfless dedication to the public interest. Cooke et al. (2019) confirmed that civil servants with high PSM were more highly engaged in their tasks than those with low PSM. Thus, the following hypothesis is proposed: H 8 : Public service motivation positively influences civil servants' employee engagement.
According to SET theory, its central assumption is the norm of reciprocity (Blau, 1964). When organizations initiate the exchange, they are able to offer resources that are valued to their employees. Based on these valued resources, employees could easily learn skills and abilities to match the requirements of the job. As a result, civil servants will have a meaningful experience while performing the job and, therefore, are likely to reciprocate with higher levels of job engagement. In other words, the more satisfied employees are in terms of their jobs, the more likely they are to become engaged in their tasks in order to achieve the goals of the organization. Therefore, the following hypothesis is suggested: H 9 : Job satisfaction positively influences civil servants' employee engagement. Macey et al. (2011) stated that job engagement forms a positive, fulfilling, and work-related state of mind that is typified by absorption, vigor, and dedication. It is a mechanism that allows an explanation for how motivation leads to employees' results. When employees engage fully in their duties, they tend to exhibit high levels of mental resilience, energy, and passion as well as putting forth effort toward fully completing tasks. Similarly, Avery et al. (2007) also agreed that civil servants with high engagement, feel an emotional connection to the success of the organization which results in enhanced productivity. Consequently, the following hypothesis is posited: H 10 : Employee engagement positively influences civil servants' job performance.

The mediating role of public service motivation
According to Gronn (1997), TL has the strongest positive relationship with increased job-related outcomes (e.g., job satisfaction, engagement, and performance). This leadership style working in tandem produces the greatest results. The varied and yet synchronous views within the leadership literature support the ideology that leadership practices play a role in job-related outcomes. The specific type of leadership may depend upon the environment, the work group, or the employee. Prior studies have shown that relationships exist between TL and JP (Sürücü et al., 2022), TL and PSM (e.g., Jensen & Bro, 2018), and PSM and JP (e.g., Miao et al., 2019). What is clear is that TL positively relates to PSM which positively relates to job-related outcomes (e.g., job satisfaction, engagement, and performance). Linking the associations outlined above, the author argues that there is a likelihood that PSM mediates the effect of TL on JS, EE, and JP. Based on the previous studies, it is hypothesized that:  Hofstede (2001) defined power distance as "the extent to which less powerful members of a society accept and expect that power is distributed unequally". Kirkman et al. (2009) stated that researchers need to distinguish between power distance at the individual and country levels. They also suggested that "power distance orientation" presents power distance at the individual level. Therefore, it's regarded as an individual-level construct. Kirkman et al. (2009) advocated that PDO had a more theoretically direct connection to leadership reactions than other cultural values (e.g., "individualism-collectivism," "uncertainty avoidance", and "masculinity-femininity"). An individual with high PDO tends to accept more and is more receptive to the top-down direction (or a hierarchy) from his/her leaders. Similarly, Hofstede (2001) also emphasized that subordinates with a high PDO expect power to be distributed unequally and they believe that it is acceptable for leaders to have a great level of power over subordinates. In opposition, an individual with low PDO tends to try distributing power equally and builds up a strongly personal connection with his/her leaders; the lines of authority are blurred in his/her relationships. Bass and Riggio (2006) maintained that "whether leadership emerges and is successful and effective depends to some extent on the environment, the organization, the tasks and goals involved, and the distribution of power between the leaders and the followers". They argued that transformational leaders regularly inspire subordinates in challenging ways and the leaderfollower relationship is two-way. It is hypothesized that civil servants with a high PDO would be slightly intrinsically motivated, satisfied, engaged, and effective when working with a transformational leader. Civil servants with a high PDO expect their supervisors to communicate strong directives with more clarification or explanation about their job, but transformational leaders attempt to intellectually inspire subordinates by challenging them to re-examine expectations about their tasks or rethink how their tasks can be performed. Thus, this could lead to suspicion by such subordinates. Conversely, an employee with a low PDO would be more intrinsically motivated, satisfied, engaged, and effective when his/her supervisors ask him/her to reexamine assumptions about his/her work and think how his/her job can be better performed as he/she does not prefer the top-down approach. Therefore, a civil servant with low PDO could improve behavioral outcomes (e.g., public service motivation, job satisfaction, engagement, and performance) when he/she works with transformational leaders (Vuong & Hieu, 2023). According to the above discussion, the following hypotheses are proposed (Figure 1):

Measurement
All variables in the conceptual model were measured with multi-item scales, which were developed by previous researchers. The author employed a Likert scale of 5 levels, with (1) Strongly disagree, (2) Disagree, (3) Neutral, (4) Agree, and (5) Strongly agree. In particular, transformational leadership is measured by five items of Wright et al. (2012). Public service motivation was developed by the five-item Merit Systems Protection Board (MSPB) scale of Wright et al. (2013). Job performance was measured by four items of Dizgah et al. (2012). Job satisfaction was measured by four items of Giao et al. (2020b). Employee engagement was measured using the six items of Schaufeli et al. (2006). The power distance orientation scale was measured by five items of Kirkman et al. (2009).

Procedure and sampling size
In this study, the author used both qualitative and quantitative research. Firstly, from the literature review and previous research, the initial items measurement scale was generated. Then it was translated into Vietnamese to make a draft questionnaire which was used in group discussion. Besides, these items were also back-translated with the support of several English language experts. A focus group with 10 civil servants (five leaders and five employees) was conducted to adjust scales. Due to differences in culture, society, and specific business fields and careers, it is possible that the original scales that have been inherited are not really suitable for the research objects and contextual survey. Therefore, scales needed to be adjusted to suit this study. After that, the questionnaire was sent to 50 other civil servants who are currently working in the local governments in Ho Chi Minh City to retest the fitness. The measurement scale was accessed for reliability of scale by using SPSS software, version 23 (Table 1).
Cronbach's Alpha coefficient was employed to verify reliability for measurement scales. Hair et al. (2019) proposed that it should be greater than 0.7 to be acceptable. Additionally, Vuong and Giao (2020) also stated that "the corrected item-total correlation should be more than 0.3". In Table 1, the minimum value of Cronbach's Alpha and corrected item-total correlation coefficients of all scales were 0.796 and 0.456 respectively. These values were higher than the threshold. Therefore, the scales were reliable, and they were employed to collect data in the main survey.
Quantitative research was carried out through an online survey (docs.google.com) and face-toface survey questionnaires. Samples in the quantitative study were selected by the convenient sampling method. The target population was civil servants currently working in local governments in Vietnam. After collecting questionnaires, 271 questionnaires were collected directly from respondents. There were 386 questionnaires collected by an online survey while 52 questionnaires were excluded from the study because some items from these questionnaires were unanswered or answered with the same mark for all items. Finally, 605 valid questionnaires were used to analyze some demographic characteristics as shown in the following table (Table 2).

Partial least squares regression
The partial least square-structural equation modeling (PLS-SEM) was used to test the hypotheses via the SmartPLS 3.0 software program. Hair et al. (2019) stated that "PLS is an approach which can contribute much utility for causal analysis in behavioral research. It is also a powerful multivariate technique which scrutinizes complex research problems that include unobserved variables". PLS is suggested for complex models focused on prediction since it works well with minimal demands on measurement scales, small sample sizes, and residual distribution. Besides, PLS-SEM can compute complex analysis on latent variables, including testing of indirect effects and multiple moderation effects, of which there are several in this study, and there is no need for additional quality of fit tests like the covariance-based structural equation model requires. Hair et al. (2019) suggested that the researchers should use Composite Reliability (CR) and Cronbach's Alpha (CA) coefficients to assess reliability for all of the latent variables. A value of these coefficients of at least 0.7 is acceptable to consider that a construct is reliable. In this study, the CA value of the latent constructs ranged from 0.787 to 0.881 (for example, job performance, and public service motivation). Besides, the CR values were larger than 0.7 (Table 3). Thus, the author verifies that the scales had good reliability.

Research result
While reliability deals with consistency, validity concerns accuracy. Hair et al. (2019) recommended that convergent validity could be acceptable when the outer loadings are above 0.50. The result indicated that the minimum outer loadings of all constructs were 0.539 (for example, outer loading for PDO5 = 0.539).
Additionally, Vuong and Giao (2020) suggested that AVE values should be more than 0.5 to assess the convergent validity for each of the latent constructs. Table 3 reported AVE values for each of the constructs. All constructs were higher than 0.5 for AVE. Consequently, each of the variables showed good convergent validity. Furthermore, Fornell and Larcker (1981) recommended that "discriminant validity is found when the square root of AVE for each latent variable is higher than other correlation values among any other construct". Table 3 showed the square roots of the AVE values (in the parentheses) that were higher than the off-diagonal correlations. For example, "Job satisfaction" had an AVE of 0.677 (See ,  Table 3), and the square root of the AVE for "Job satisfaction" was 0.823 in the Fornell-Larcker Criterion (See, Table 3). As stipulated, 0.823 was both higher than the correlation values in its column (0.098, 0.567, −0.013, 0.088, and 0.473) and its row (−0.031, 0.399, 0.532, and 0.472). Thus, the discriminant validity of the constructs has been confirmed.
Finally, the Common Method Bias detection will be confirmed through the full collinearity assessment approach. The expected range of this assessment, called the VIF statistics, is lower than the 5 thresholds, indicating that the model is free of common method bias (Giao & Vuong,   Table 4, all VIF values were below the threshold of 5; the maximum value of outer VIF was 4.046 (less than 5), and the maximum value of inter VIF was 2.481 (less than 5) indicating that the model is free from common method bias, meaning there were no problems with multicollinearity.
Results from the PLS-SEM analysis were revealed in Figure 2. Standardized path coefficients and p-values were reported in Table 5. The results were shown as follows: Hypothesis 1: The result revealed that TL had a positively strong impact on the JP of civil servants with a regression weight of 0.254 and p-value = 0.000, which means that the more effective the TL, the greater the possibility that civil servants will achieve high JP. This result was consistent with the findings of Sürücü et al. (2022). Thus, hypothesis 1 was supported.
Hypothesis 2: The finding indicated that TL had a positive influence on PSM with a standardized coefficient of 0.400 and p-value = 0.000, which means that the more effective the TL, the greater the possibility that civil servants will achieve high PSM. According to these results, the author argues that followers who work with transformational leaders may have more interaction with leaders: vision needs to be communicated as it helps give direction for what they are doing; they also need to learn how to become a good employee by reflecting their leaders' model; besides they may need their leaders to get consensus from the group. Therefore, performing TL behaviors with followers may significantly boost their PSM level. This result corresponded with some prior researches (Jensen & Bro, 2018;Wright et al., 2012). Therefore, hypothesis H 2 was supported.
Hypothesis 3: The result showed that PSM had a positive effect on JP with a standardized coefficient of 0.198 and p-value = 0.000, which means that the higher the PSM, the greater the possibility that civil servants will achieve high JP. It was also linked to the prior researches of Miao et al. (2019). Therefore, hypothesis H 3 was supported.
Hypotheses 4, 5, and 6 presented positive effects of TL and PSM on JS, as well as a positive relationship between JS and JP of civil servants. As shown in Table 5 above, the sequentially standardized coefficient was 0.308; 0.408; 0.153, and the p-values were 0.000 (less than 0.05), which means that the more effective the TL and the higher the PSM, the greater the possibility that civil servants will get high JS. Moreover, when civil servants satisfy their job, they tend to reach high JP. Hence, hypotheses H 4 , H 5, and H 6 were supported.
Hypotheses 7, 8, 9, and 10 displayed positive influences of TL, PSM, and JS on EE, as well as a positive association between EE and JP of civil servants. As shown in Table 5 above, the sequentially standardized coefficient was 0.141; 0.534; 0.216; 0.170, and the p-values were less than 0.05, which means that the more effective the TL and the higher the PSM and JS, the greater the possibility that civil servants will engage in their tasks. Moreover, when civil servants exhibit high engagement in their job, they tend to reach high JP. So, hypotheses H 7 , H 8 , H 9, and H 10 were supported. This research has been conducted exploring demographic variables (e.g., gender, marital status, age, and educational level) in conjunction with job performance of civil servants. Table 5 indicated that the differences between the mean of control variables were not statistically significant. This research did not find a relationship between job performance and gender (p = 0.438; β = 0.024), marital status (p = 0.171; β = 0.041), age (p = 0.644; β = −0.016) or educational level (p = 0.355; β = 0.029).
Hypothesis 11a: PSM mediates the relationship between the TL and JS of civil servants in Vietnam. First, the results in Table 5 showed that the direct relationships between "TL and PSM" and "PSM and JS" existed because the p-value for the path TL→PSM was 0.000; PSM→JS was 0.000 (less than 0.05). Second, after bootstrapping, the value of the p-value for the indirect effect between TL→PSM→JS (Table 6) was 0.000 (less than 0.05). It demonstrated that the indirect relationship between TL and JS through PSM occurred as well. Therefore, it revealed the mediating role of PSM on the relationship between TL and JS. Moreover, the direct effect of TL and JS still existed (β = 0.254 and p-value = 0.000, Table 6) when PSM was integrated into the model. Therefore, the type of mediation was partial. Consequently, the total influence of TL on JS (direct and indirect effect) was 0.333 (p-value = 0.000). This result indicated that TL could strongly improve JS when civil servants feel motivated in their job. Additionally, most prior studies only confirmed the direct effect of TL on JS. In this study, the authors provided evidence about the PSM construct played as the mediating mechanism on the relationship between TL and JS. Therefore, TL cannot automatically be considered as high satisfaction. It can be clearly understood that civil servants believe TL improved their satisfaction with their job if their PSM is shown. Therefore, hypothesis H 11a was supported.   Hypothesis 11b and 11c: Similarly, based on the results in Tables 5, 6, and Figure 2, public service motivation mediated the relationships between "TL and EE" and "TL and JP". These types of mediation were partial. In other words, civil servants believe TL improves their engagement and performance if their PSM is exposed. Therefore, hypotheses H 11b , and H 11c were supported.
Hypothesis 12a assumed that the relationship between TL and PSM will be moderated by PDO, so this positive association will be weaker for civil servants who hold a high PDO. As shown in Figure 3 and Table 7, the interaction effect of TL * PDO (moderating effect 1) had a significant influence on PSM with path coefficients of −0.124 and a p-value of 0.000 (less than 0.05). Besides, TL impacted positively on PSM. Therefore, high PDO dampened the positive relationship between TL and PSM ( Figure 4). Thus, hypothesis H 11a was supported.
Hypothesis 11b assumed that the relationship between TL and JS will be moderated by PDO, so this positive association will be weaker for civil servants who hold a high PDO. As shown in Figure 3 and Table 7, the interaction effect of TL * PDO (moderating effect 2) had a significant influence on  JS with path coefficients of −0.060 and a p-value of 0.030 (less than 0.05). Besides, TL impacted positively on JS. Therefore, high PDO dampened the positive association between TL and JS ( Figure 5). Thus, hypothesis H 11b was supported.
Hypothesis 11c assumed that the relationship between TL and EE will be moderated by PDO, so this positive connection will be weaker for civil servants who hold a high PDO. As shown in Figure 3 and Table 7, the interaction effect of TL * PDO (moderating effect 3) was insignificant on EE with path coefficients of −0.004 and a p-value of 0.887 (more than 0.05). Thus, hypothesis H 11c was not supported.
Hypothesis 11d assumed that the relationship between TL and JP will be moderated by PDO, so this positive relationship will be weaker for civil servants who hold a high PDO. As shown in Figure 3 and Table 7, the interaction effect of TL * PDO (moderating effect 4) had a significant influence on job performance with path coefficients of −0.072 and a p-value of 0.011 (less than 0.05). Besides, TL impacted positively on JP. Therefore, high PDO dampened the positive relationship between TL and JP ( Figure 6). Thus, hypothesis H 11d was supported.
For model fit, Hair et al. (2019) recommended that Coefficients of determination (R 2 ) should be used to measure the predictive accuracy in the structural model. After analysis, the R 2 coefficient for JP was 0.385, which indicated that 38.5% of the total variation of JP may be explained by TL, JS, EE, and PSM (See , Table 3). Similarly, 19.4% of the total variation of PSM may be explained by TL;  36.3% of the total variation of JS may be explained by TL, and PSM; 56.9% of the total variation of EE may be explained by TL, JS, and PSM. Furthermore, Vuong and Giao (2020) defined the values of under 0.02 as weak, from 0.13 to 0.26 as moderate, and greater than 0.26 as substantial. The findings showed that the R 2 value for JP was greater than 0.26. Thus, the model of this research verified the good model-data fit.

Conclusion
The objective of this research was to examine how transformational leadership affects public service motivation, and how it influences job-related outcomes (e.g., job satisfaction, engagement, and performance). This study helped enhance and expand our understanding of civil servants' perception of TL and PSM. A survey of 605 civil servants with different characteristics was collected. Civil servants from the Vietnamese local governments participated and exhibited their perceptions of TL, PSM and job-related outcomes in Vietnam. The finding of this study indicated correlations between a system of constructs. First, if a civil servant perceives effective TL in his/her workplace, he/she displays high PSM. This PSM leads to high satisfaction, high engagement, and high performance with his/her job. Moreover, when civil servants are satisfied, they tend to be more engaged and productive at work. The findings were congruent with previous researches about the positive effects of transformational leadership on job satisfaction, employee engagement, and job performance. Second, studying TL is important to the Vietnamese local governments in managing and leading organizations. This research has contributed to the literature with the model explaining the TL influence on PSM and job-related outcomes in Vietnam. Besides, the model was developed on the conceptual literature of prior scholars. The scale items were surveyed in developed countries, and this research was modified to match the Vietnamese situation through practical data collection. Thus, this study contributed to the literature and helped researchers to have a better understanding of Vietnam's situation. Theoretically, the research framework used in this study confirmed that some previous studies on the relationship between TL and job related outcomes in Western cultures could also be generalized in the Vietnamese setting.
In addition, the authors also included a promising moderating variable, power distance orientation. The current study added to researchers' effort to examine PDO at the individual level of analysis to ascertain the generalization of cultural value orientation and TL effects. Therefore, the aim is concerned with the moderating effect of the follower's PDO on the relationship between TL and behavioral outcomes. The findings also discovered the moderating effects of PDO on the impacts of perceived TL on PSM, JS, and JP. Civil servants with high PDO tended to dampen the positive relationship between TL and PSM as well as decreased JS and JP. The possible explanation of this may be related to the dual nature of PDO values. On one hand, employees with high PDO may resist practices incompatible with their cultural values. Alternatively, those employees have a tendency to obey their managers and follow directions without hesitation. Therefore, these values could cause resistance to management initiatives. Moreover, although TL may produce desirable effects in the long run, in the short run, administrators may continually exhort or urge employees with high PDO to search for better and new approaches of doing things from conflict and ambiguity in the minds of those employees. After the increased job demands created by a transformational leader increase conflict, ambiguity, and stress, the authors may recognize that PSM, JS, and JP decrease with high PDO-oriented followers.

Policy implication
This study examined the relationship between TL and behavioral outcomes in the Vietnamese context represented by the respondents from local governments. Based on the findings of this research, the authors expect to provide some meaningful policy implications for public managers at Vietnamese local governments who try to have a better understanding of the behavioral outcomes of civil servants in the workplace. To do so, the most vital way is to understand the concept of TL that leads to implementing the right pathways or strategies. Hence, this research makes an attempt to offer a few insights for the public managers as follows: First, TL positively connected with subordinates' PSM, JS, EE, and JP. The authors recommend the need for more transformational leaders in Vietnamese local governments because leaders who use it will be able to increase their organization's performance. To promote and foster the development of PSM and employees' job related outcomes, public managers should gain trust from organizational members by exhibiting full commitment to achieve organizational objectives and act as a good role model. Public leaders should pay attention to subordinates' needs, desires, and abilities. Besides, they need to provide a supportive environment and help subordinates develop their talent. Furthermore, the employees' jobrelated outcomes could also be increased when public leaders' ideas and creative problem solutions are considered when addressing problems and finding solutions. When leaders apply intellectual stimulation, employees feel comfortable and safe in expressing their opinions, hence outcome levels increase as well. To achieve these improved outcomes, local governments should train and develop transformational leadership competencies for administrators at all levels of the organization so that they will know how to implement transformational leadership in the workplace.
Second, PSM is likely to benefit organizations in many ways. Higher PSM levels have been linked to increased job-related outcomes (e.g., job satisfaction, engagement, and performance). By analyzing civil servants, this study provides some helpful information to managers in local governments in terms of a baseline for PSM. Public managers should determine how to enhance and foster PSM in civil servants. Many of the prior studies on employee motivation emphasis on the use of pay as a motivating utilitarian reward; however, the average salary in the public sector is quite low in Vietnam (around $200/per month), the Vietnamese government cannot use monetary incentives to promote public service motivation of civil servants due to a limited budget. Therefore, the results of this study suggest that public managers who are attempting to attract individuals with high PSM levels may be well served by concentrating on other incentives (e.g., transformational leadership).
Finally, the authors found that power distance orientation was a statistically significant moderator of the relationship between TL and follower's PSM, and job-related outcomes (e.g., job satisfaction and performance). The findings indicated that the influence of leadership behaviors on follower's public service motivation and job-related outcomes was partly contingent on a follower with high PDO. One of the practical implications is that leaders should be available for their followers and proactively spend time coaching and teaching and helping their new staff to better understand their values and behaviors, which can be passed on to their followers. In addition, public leaders should encourage civil servants' innovative thinking, consider employee personal feelings before implementing a decision, and help the followers to develop their strengths. This could help to increase the level of emotional attachment that civil servants have with the local governments as well as diminish the power distance between the leader and the subordinate in the workplace. When civil servants feel pride to be part of their organization and find similarity between their own values and the organization's values, they will be ready to exhibit more public service motivation, which in turn increases the productivity and profitability of the organization as well as citizens' satisfaction.

Limitations and recommendations for future research
There are various limitations of this study. Recommendations for future research will be also discussed. First, the study was conducted in Vietnam. Future research should replicate the study in other cultures. Second, the respondents of this study had relatively high levels of education. Accordingly, replication of the study should involve a sample with diversified education levels to better capture the variance in public service motivation among follower groups with different educational backgrounds. Finally, this research only assessed the moderating variables of power distance orientation on the effects of transformational leadership on public service motivation, job satisfaction, and job performance. Future research should investigate the moderating roles of other components of cultural values such as "individualism-collectivism," "uncertainty avoidance", and "masculinity-femininity".

Items
In most situations, managers should make decisions without consulting their subordinates In work-related matters, managers have a right to expect obedience from their subordinates Employees who often question authority sometimes keep their managers from being effective Once a top-level leader makes a decision, people working for the organization should not question it Employees should not express disagreements with their managers