Job Satisfaction and Labor Fluctuation: A Case Study in the Logistics Sector in Serbia

: Background: There is a growing need for logistics professionals in different positions and with different competencies. The key question is how to attract and retain a highly skilled work-force. The purpose of this research is to determine what factors and how they affect employee’s satisfaction and loyalty in the logistics sector in the Serbian market; Methods: The impact of company size, primary business activity and employee position on labor loyalty and fluctuation were examined. The research hypotheses were tested on the basis of data obtained from a web survey that included 270 respondents from different industrial sectors in the Serbian market. Linear regression was used for hypothesis testing; Results: The results showed, among other things, that salary and advancement possibility are the main motives for changing jobs. The importance of basic professional knowledge acquired at the faculty for employment and working in various companies was confirmed; Conclusions: There are no papers in the literature that investigate job satisfaction and employee turnover in the logistics market. The results of this research, on the one hand, provide useful and accurate information for decision-making in order to improve the situation in the observed market, while on the other hand, provide an excellent basis for future research.


Introduction
The importance and role of logistics in the economic development of the country have been recognized a long time ago.The logistics sector is characterized by a very dynamic market with strong competition and constant changes.Changes at the global, regional and national level directly affect changes in the logistics sector.Recently, labor has been stated as one of the main problems in logistics.In the literature, more emphasis is placed on human resource management in logistics and supply chains [1][2][3].Regardless, the area is still under-explored.In Ref. [4]. the authors point out that very few papers in the field of logistics and supply chains address these issues.On the one hand, the human resource problem is a problem common for all companies and all markets.On the other hand, each market is characterized by specific characteristics that may not be present in other markets (countries) [5,6].
In this respect, this paper explores the labor force in the logistics market of Serbia in more detail.As a developing country, with an extremely favorable position, Serbia has great potential in logistics, but also great challenges that arise in the logistics sector.Fluctuation and labor shortage are one of the major problems [7][8][9][10][11].The subject of research is logisticians (faculty-educated experts who are responsible for the implementation and realization of logistics activities and processes) in companies in Serbia.The results were collected through a survey.In addition to job satisfaction, the skills, knowledge and education of logisticians in Serbia were also examined [11][12][13][14].Special emphasis has been given to the development and retention of young talents through student practice and career guidance [15,16].Among other things, the aim of the paper is to examine the main motives for changing jobs, as well as the effect of job satisfaction on a job change, the main factors of job satisfaction, the necessary skills and knowledge to perform logistics tasks, as well as ways (means) of practice realization.
The paper is organized as follows.After the introduction, a review of the literature is presented, which is the basis for the development of hypotheses for the Serbian market.A description of the model and measurement instrument is presented in Section 2. Collected data and the results of hypothesis testing are then presented in the next section.Section 4 provides theoretical and practical implications.At the very end of the paper, concluding remarks and directions for future research are outlined.

Problem Description and Hypothesis Development
Since there is no research in the field of human resources in logistics, the aim of this paper is to close this gap.Some authors emphasize the need to investigate this problem in particular markets with particular emphasis on developing countries [5].Six major dimensions have been identified based on the state in the literature and relevant practical knowledge.For each of the dimensions, certain attributes are defined (Table 1).

Dimension Attributes References
Labor fluctuation -Number of companies the employee worked for -Main motives (reasons) for changing the company -Employee loyalty to the company [7,8,10,11,[17][18][19] Job satisfaction -The number of positions that employee changed in one company -Average earnings at the current position [20][21][22] Education, knowledge and skills -Primary education-completed faculty -Additional education-external and internal courses, seminars and trainings -Expected competencies (knowledge and skills) from students when they graduate -The desirable form of student practice (financing and method of realization) [4,5,11,13,15,16,23 [16,32,33] The research concerned employees in companies of different sizes, different primary business activities in the logistics sector and at different positions in companies.In this regard, several divisions of companies in which logisticians work in the Serbian market were made.In terms of size, companies can range from only a few employees, over hundreds to over a thousand employees.In this paper, companies are grouped by size into three groups: small, medium and large.By business activity (market segment) companies in which logistics activities in Serbia are carried out are grouped into several segments: distribution and domestic transport; international logistics, transport and freight forwarding; production; retail; contract logistics-3PL.Position and titles in the logistics sector in Serbia are numerous and vary from company to company; this paper also identifies and analyses the following positions: Assistants (Coordinator, Logistics Assistant, Logistics Visor and Supervisor), Managers (Logistics Manager, Supply Chain Manager, Logistics Operations Manager and Transport Manager) and Sales (Customer Service and Sales Agents).Based on the literature, information on the logistics sector in Serbia and previous experience, hypotheses have been defined within each dimension.

Fluctuation
The problem of labor fluctuation and job change has been recognized in the literature [10,18,19].One of the biggest challenges for logistics companies in China is the problem of retaining the workforce and reducing employee turnover [7,8,11].Authors in Ref. [34] define fluctuation as the quotient of those who left and the average number of workers over the observed time period.Labor fluctuation is very expressed in the logistics sector of Serbia.
Several studies have examined the impact of job experience on the current position of the employee [32,33]; this paper also assumes that previous experience gained in other companies has a significant impact on the current position.It has also been hypothesized that in a certain way, this directly affects the increase in employment opportunities.In this regard, the following hypothesis was developed:

Hypothesis 1a (H1a). Previous experience from other companies has an impact on the current position when hiring.
Various reasons for a job change and job dissatisfaction have been cited in the literature [24,27,35].In this paper, motives for changing jobs in different market segments have been explored.It is assumed that there are some differences in the motives for changing job depending on whether logisticians work in international logistics, transport and freight forwarding; distribution and domestic transport; retail; production or contract logistics-3PL.According to this, the following hypothesis was developed:

Hypothesis 1b (H1b). The motives for changing jobs vary depending on the business activity (segment) of the company.
The importance of employee loyalty to the company is recognized both in the literature [28] and in practice.By creating loyal employees, companies can achieve multiple benefits.In this regard, the importance of loyalty in companies operating in Serbia is recognized in this paper.According to this, the following hypothesis was developed: Hypothesis 1c (H1c).Employee loyalty depends on the size of the company.

Job Satisfaction
Job satisfaction is one of the main prerequisites for retaining workers.The problem has been recognized in the literature [20][21][22].The possibility of advancement and salary has been cited as key factors for job satisfaction in the literature.The possibility of advancement in the company, on the one hand represents the personal satisfaction of every employee, while on the other hand, it is an excellent indicator of the level of development and "working environment" of the company as a desirable environment for working.Based on the literature [29,30], it has been hypothesized that advancement varies greatly across segments and companies with a different number of employees; therefore, the following two hypotheses were developed: Hypothesis 2a (H2a).Advancement in the company differs depending on the company's business activity.

Hypothesis 2b (H2b).
Advancement in the company depends on the size of the company.
Salary as a basic indicator of job satisfaction has been recognized both in the literature and in practice [5,20,21].Salaries in the logistics sector in Serbia differ from the business activity (market segment) and the size of the company.In this regard, the following hypotheses were developed:

Hypothesis 2c (H2c). Salary varies depending on the business activity (segment) of the company.
Hypothesis 2d (H2d).Salary varies depending on the company size.

Education, Knowledge and Skills
Nowadays, education, knowledge and skills are acquired throughout the whole career.Primary education is the basis for further training.External and internal courses, seminars, trainings and other similar activities are important to the employees in this regard [23,36,37].Through these trainings, on the one hand, the ability of workers to perform jobs is increased, while on the other, employee satisfaction is also increased [4]; moreover, if the training is inadequate there is always a risk of errors [38].The importance of knowledge on the efficiency of the company's business is shown by numerous studies that emphasize that internal learning (training) helps to create or acquire valuable knowledge.Knowledge also represents an essential resource to enhance logistics value by improving operational efficiency and service quality [39]; moreover, enhanced knowledge transfer may promote job satisfaction which is linked to better productivity [40].On the other hand, training and development supports the learning process by providing employees new knowledge which then enables the sharing of the newly acquired knowledge [41].Besides that, knowledge resources are important for enhancing competitive advantage.Based on the results of the Ref. [42] it can be concluded that knowledge resources are positively related to cost advantages which are achieved through the ownership of professional, experienced, knowledgeable, skilled and trained employees; these opportunities may vary depending on the size of the company and the position of the employee.In this regard, the following hypotheses were developed:

Hypothesis 3b(H3b). Opportunities for additional education and training vary depending on the current position of the employee.
In order to increase job satisfaction and reduce fluctuation, it is very important to manage talents and practice before hiring and getting formal and permanent employment [5,15,16].Career planning and guidance is a very important and lengthy process.As the most important factors in this research expected and desirable competencies upon graduation, the form of practice realization and financing of the talents are identified.It was assumed that the expected and desirable competencies were not the same: in all segments of the logistics sector, in all positions and in companies of different sizes.Regarding this, the following hypotheses were developed:

Hypothesis 3c (H3c). Expected and desirable competencies upon graduation depend on the primary business activity of the company.
Hypothesis 3d (H3d).Expected and desirable competencies upon graduation depend on the size of the company.

Hypothesis 3e (H3e). Expected and desirable competencies upon graduation depend on the employee's position in the company.
As mentioned earlier, funding plays a very important role in retaining, satisfying and creating talent loyalty [4,23].In this regard, talent financing was explored in different segments of the logistics sector, as well as at different positions.The following hypotheses were developed:

Hypothesis 3f (H3f). Talent financing and practice realization depend on the primary business activity of the company.
Hypothesis 3g (H3g).Talent financing and practice realization depend on the position.

Methodology
On the basis of a systematic review of the literature, information from industry and previous experience and previous research of the authors [43], a construct was defined to measure job satisfaction and examine the causes of expressed employee turnover.The basic dimensions identified in this paper are: labor fluctuation; job satisfaction; education, knowledge and skills; primary business activity; company size and employee position (Figure 1).Based on the developed construct, an appropriate questionnaire was created.The questionnaire was used as a data collection tool.The questionnaire was composed of two parts, where the first part of the questionnaire included questions to determine the characteristics of the respondents and the companies in which they work, while the questions in the second part were asked in order to determine job satisfaction and employee turnover (Table 2).In order to process the results, a 5-point Likert scale was used for each question (5 = strongly agree; 4 = agree; 3 = neutral; 2 = disagree; 1 = strongly disagree).As mentioned earlier, the questionnaire was intended for logisticians in Serbia.An electronic version of the questionnaire was sent to 310 addresses, which were taken from the author's database that has been collected over the years in cooperation with numerous logistics associations and companies.The survey was conducted in the period from November 2021 to January 2022.A total of 310 completed questionnaires were collected.After selective analysis, responses that were not completely filled were excluded from further analysis which ended with 270 fully filled questionnaires.A sample of 270 responses was then statistically processed.Based on these results and Table 2 it can be concluded that respondents work in different companies and in different positions.About 46% of the respondents are employed in international logistics and freight forwarding, while others work in distribution and domestic transport (9.17% of respondents), production (21.40%), contract logistics-3PL (9.61%) and retail (13.10%).When regarding the size of the company, most of the respondents are employed in companies with over 1000 employees (34.07%), followed by companies with 150-300 employees (27.76%).The smallest number of respondents are employed in companies with 600-1000 employees (4.73%).From the aspect of the position of the respondents, three groups are dominant: Logistics Manager (19.80%),Transport Manager (18.81%) and Logistics Assistant (16.83%).Answers to question related to the years of work experience of the respondents showed that over 60% of the respondents have 3-7 years (35.33%) or 7-15 years (30.91%) of working experience.
The reliability test showed that all of Cronbach's α were greater than 0.731, indicating an acceptable level of internal consistency between items.In this study, unidimensionality was assessed first by using the following goodness of fit indices: normed chi-square (ᵪ2/df), goodness-of-fit index (GFI), adjusted goodness-of-fit index (AGFI) and root-meansquared error of approximation (RMSEA) [6].The values of the aforementioned indices are following ᵪ2/df = 2.445, GFI = 0.940, AGFI = 0.911 and RMSEA = 0.068.Another rule of thumb suggesting adequate convergence is that the average variance extracted (AVE) for all constructs should be greater than 0.5 [6].For all constructs in this paper, AVE values have crossed the threshold of 0.5 and are 0.514; 0.608; 0.708 and 0.579 for fluctuation; job satisfaction; education, knowledge and skills; talent management and loyalty creation, respectively.

Results
Based on the hypotheses developed in Section 2, this section analyses the results of their testing in more details.Testing was performed using linear regression [44,45].The results of the linear regression are shown in Table 3.In this paper three independent and three dependent variables were used.Primary business activity, company size and position are independent variables, while dependent are labor fluctuation, job satisfaction and knowledge, education and skills.Based on the results (Table 3) and the value of β = 0.109, p < 0.1 the existence of a correlation of previous experience with the current position in the company was confirmed, which is consistent with Ref. [46].Employees with more work experience have better positions in companies which was also proven by the results of the survey, which showed that respondents with more than 7 years of work experience are predominantly in senior positions (director, CEO, director of logistics, director of operations, supply chain manager, logistics manager, etc.).On the other hand, respondents with a work experience of up to 3 years are generally working at positions such as logistics assistant, coordinator, logistics visor and supervisor, planner and specialist; this may further lead to the conclusion that gaining experience is crucial for the career development and progression process.The chances of employment are greater if the experience is greater.On the basis of all previously said, it can be concluded that hypothesis H1a is supported.
According to the results (Table 3) and the value of β = 0.138, p < 0.05, a difference in the motives for changing jobs in different market segments was found, which is in accordance with Ref. [24].Based on the results of the survey, it was found that the main motive for changing the company, among the respondents who are employed in companies dealing with distribution and domestic transport as well as contract logistics-3PL is salary, while inability of advancement is the main motive for employees working in production and trading companies.The respondents working in companies dealing with international logistics, freight forwarding and transport as the main motives for changing the company emphasized salary and inability of advancement.Besides salary and inability of advancement, motives such as poor interpersonal relationships and hard and stressful work were also recognized; this way, hypothesis H1b is also supported.
Based on the results in Table 3 and the values of β = 0.134, p < 0.05, it was confirmed that there is a difference in the loyalty of employees in medium and large companies compared to employees in smaller companies (H1c).The results of the conducted research show that employees in medium and large companies are more loyal (over 50% of respondents spent more than 10 years in one company) compared to employees in small companies (where 78% of respondents spent less than 5 years in one company).The results obtained are consistent with previous research [28].
The values of β = 0.104, p < 0.1 for hypothesis H2a and β = 0.267, p < 0.01 for hypothesis H2b indicate that both hypotheses (H2a and H2b) are supported (Table 3).The results are in accordance with the results in Ref. [22].The aforementioned authors have shown the influence of motivation on job satisfaction, as well as that status and advancement can negatively affect job satisfaction.Advancement in companies dealing with international logistics, freight forwarding and transport as well as in companies dealing with contract logistics-3PL is the slowest since the respondents working in these companies have changed only one or two positions.On the other hand, advancement in companies dealing with distribution and domestic transport and trade is faster, since respondents working in those companies stated they have changed three or more positions.Advancement also depends on the size of the company, as evidenced by the survey results.Namely, in small companies (up to 50 employees) the largest percentage of respondents (60% of them) changed only one position.In medium-sized companies, the largest number of respondents (70% of them) changed up to two positions.The largest number of positions, i.e., two or more were changed by respondents in large companies (81%).
According to the results obtained in Table 3 and the values of β = 0.114, p < 0.05 the existence of wage differences in different segments was confirmed.Based on the survey results, the lowest salaries (up to EUR 700) have employees in companies dealing with distribution and domestic transport as well as in international logistics, freight forwarding and transport.Salaries from EUR 700-1000 have employees in trading companies as well as in contract logistics-3PL.The highest salaries (over EUR 2000) have respondents in international logistics, freight forwarding and transport and manufacturing companies, which is consistent with Refs.[25,26].The results of a study conducted in Ref. [26] show that wage differences also exist in many European countries.Salary difference is present not only depending on the primary business activity but also on the size of the company, which is in accordance with Ref. [31].The results of the survey show that the smallest salaries (up to EUR 700) have employees in small companies.The salaries of EUR 700-2000 have employees in medium-sized companies, while the highest salaries (>EUR 2000) have employees in large companies; this way, hypotheses H2c and H2d are supported.
The results presented in Table 3 and the values of β = 0.226 p < 0.001 confirmed differences in training opportunities, which is consistent with Ref. [47].Training possibility is bigger in larger companies as indicated by the results of the survey.Namely, the largest number of respondents (30%) in small companies did not have the opportunity for improvement.Employees of medium-sized companies (28%) had up to 2 trainings, while the largest number of trainings (over five) had employees in large companies (43% of them).Significant differences in training and additional education also exist when observing positions.Namely, there are positions where these opportunities are much more pronounced than others.Based on the results of the research, it can be concluded that employees in senior positions (such as Logistics Manager, Supply Chain Manager and Logistics Operations Manager) had more training than other positions; this way, hypotheses H3a and H3b are supported.
The results of the conducted research show that employees working in companies dealing with distribution and domestic transport, production, trade and contract logistics expect from students (trainees) to have multiple skills and knowledge, such as professional knowledge, practical skills, knowledge of computer programs (such as excel, word, etc.), knowledge of the foreign language, personal characteristics, communication skills, interest in the job, motivation, persistence, etc.A similar situation is with the employees working in companies for international logistics, freight forwarding and transport, where they emphasized skills such as knowledge of basic computer programs, knowledge of the foreign language and personal characteristics.Based on the results (Table 3, β = 0.125 p < 0.05) and previously said, it can be concluded that H3c is supported.When observing the relationship between company size and expected competencies, it can be concluded that knowledge of basic computer programs, knowledge of the foreign language and personal characteristics are expected competencies for working in smaller companies.On the other hand, in medium and large companies, students are expected to have the following competencies and knowledge: professional knowledge, practical skills, knowledge of computer programs, knowledge of the foreign language, personal characteristics, communication skills, interest in the job, motivation, persistence, etc.The results in Table 3 (β = 0.119 p < 0.05) unequivocally support hypothesis H3d.Employees in positions such as Coordinator, Logistics Assistant, Logistics Visor and Supervisor, Logistics Operations Manager and Customer Service expect the following competencies from students: knowledge of basic computer programs, knowledge of the foreign language and personal characteristics.On the other hand, employees in the positions such as Logistics Manager, Supply Chain Manager, Transport Manager and Sales expect from students the following competencies: professional knowledge, practical skills, computer skills, knowledge of the foreign language, personal characteristics, communication skills, interest in the job, motivation, persistence, etc.Based on this, it can be concluded that there is a difference in the expected competencies depending on the position of the employee in the company (Table 3, β = 0.125 p < 0.25), thus supporting the hypothesis H3e.
The results of testing the talent financing hypotheses are shown in Table 3 (β = 0.121 p < 0.05).The results of the conducted research are in accordance with previous research.Authors in Ref. [15] note the impact of career development and financial benefits.Authors in Ref. [5] used pay and welfare package to measure the reward system used by Chinese LSPs because they are closely related to attracting and retaining talent.Understanding the importance of talent financing is not the same in all segments.The results of the research show that paid practice is the most common type of practice that is dominant in almost all market segments.In addition to this type of practice, work in the presence of a mentor is another type of practice in trade and 3PL companies.In the companies dealing with international logistics, freight forwarding and transport, the defined practice program is recognized as another type of practice.Based on this, hypothesis H3f is supported.
Employees in different positions have different views on how practice should be conducted (Table 3, β = 0.131 p < 0.05).Employees in positions of Coordinator, Logistics Assistant, Logistics Visor and Supervisor and Sales believe that the practice should be paid, while employees in other positions believe that the practice should be realized either through mentoring or through a defined practice program.Talent financing is not the same in all positions, i.e., there are more and less paid positions.Bearing in mind previously said, it can be concluded that hypothesis H3g is supported.

Practical and Theoretical Implications
Based on the results obtained, as well as literature research [32], the effects and implications on the logistics sector are analyzed in more detail below.By supporting the H1a hypothesis, it has been shown that experience in the logistics sector of Serbia is a very important factor for successful performance in the most responsible positions.The analysis of the results shows that experience can be gained in different companies or in the same company.Regardless of how the experience is gained, experience presents a prerequisite for performing managerial positions.Experience also has a direct impact on increasing job opportunities and changing jobs.
After reviewing literature research, it has been found that there are not enough papers that address in more detail the reasons for the job change [24,27].Salary is one of the main motives present in almost all segments (H1b).Based on the results presented in the previous section, the following conclusions can be drawn.Companies dealing with distribution and domestic transport have to influence the increase in salary, as this is one of the main motives why workers leave companies in this sector.Salaries are higher in manufacturing and trading companies, but opportunities for advancement are lower, and this is also a major motive for changing jobs.The reason is very logical.For manufacturing and trading companies logistics is not a primary business activity, so the logistics subsystem has a simple hierarchical structure.Companies in this sector need to pay more attention to additional forms of training and employee motivation [48].These results are similar to the results of the Machová [49] where authors concluded that the most popular motivation tools proved to be the financial incentives in the form of salary increases or bonuses.Poor interpersonal relationships and stressful work greatly affect job change in freight forwarding and logistics companies, which is similar to the results of the Machová [49].It is very important that the HR service and other sectors pay more attention to this serious problem.The problem is very complex, and changes need to be made when selling services but also when promising deadlines, as well as in the development of employee relations (e.g., team building).
The difference in employee loyalty depending on the size of the company has a logical explanation (H1c).Namely, employees in medium and large companies often strive to retain in these companies because of their ability to advance and achieve personal goals [28].These companies also provide opportunities for changing sectors, which in some situations can offset an employee's desire to change jobs.On the other hand, employees in small companies retain for a shorter period, as opportunities in these companies are also smaller.
According to research in the literature, it has been established that one of the key factors that can increase employee satisfaction is the possibility to advance [20,21].The conducted research confirmed the difference in advancement in companies from different sectors (H2a), as well as the difference in advancement in large and small companies, which is in accordance with previous research [22].As advancement is the slowest in companies dealing with international logistics, freight forwarding and transport; contract logistics-3PL, it directly affects the departure of quality staff and decreases business efficiency.On the other hand, much better conditions for advancement are in companies dealing with distribution and domestic transport and trade.In practice, it is a very common case that employees from sectors with lower promotion opportunities move to companies from sectors with higher advancement opportunities; this division is also characterized by significant differences in the working environment, which is much more uncertain, stressful and demanding in the first group [50]; this is precisely the basis of action aimed at increasing employee satisfaction and retaining employees, and moreover, companies in the second group predominantly operate in the domestic market where requirements are much more predictable and easier to manage.Companies dealing with international logistics, freight forwarding and transport as well as contract logistics-3PL, need to improve the working environment, atmosphere and opportunities to advance with a series of actions [51]; moreover, managers must focus on creating sustainability culture [52].First of all, it is necessary to change the agreed (promised) deadlines for clients, which are often for no reason unreasonably short and difficult to achieve; this would greatly reduce the stress resulting from short deadlines.Employees should also be given opportunities to advance and change positions.
The differences in advancement opportunities in large and small companies described in Section 4 which supports H2b.Large companies offer greater opportunities for advancement, which is logical given their more complex structure and number of potential positions.In small companies, it is advisable to organize additional external trainings and courses that can in some way offset smaller advancement opportunities.
Salary is one the most important factors of satisfaction [5,20,21].Conducted research revealed the difference in salaries in the logistics sector of Serbia, depending on the business activity (market segment) and the size of the company (H2c and H2d).Based on the results presented in the previous section, it can be easily concluded that smaller companies need to increase salaries in order to reduce employee's leaving and relatively large fluctuation.A similar situation is also with the companies in the sector with lower salaries.In addition to changing salaries, they must affect the satisfaction of their employees in other ways, with the aim to reduce fluctuation.
Research findings on training and skills are consistent with previous research in the literature [4].Differences were noted depending on the size of the company and the position of the employee.The number of trainings in smaller companies is lower than in larger companies (H3a).Unlike advancement opportunities, the quantity of training in smaller companies must increase.Primarily, external trainings and improvement in various fields.
On the other hand, the difference in training and improvement is not the same for all positions (H3b).As stated earlier the results of the conducted research show that employees in higher positions have more trainings comparing to those on lower positions; this can by no means be considered justified and is one of the main reasons for the great dissatisfaction of employees in lower positions.Given that the salary is justifiably higher in higher positions, training must be more evenly distributed to all employees regardless of hierarchical position.
In this paper, special importance is given to talent management and employee loyalty creation at the beginning of a career [5,15,16,53].Based on the results [54] it was concluded that autonomy is a positive moderator for the impact of overeducation on job satisfaction.The skills expected of students differ by sector and are described in more detail in Section 4 (H3c).On the one hand, companies in the logistics sector can choose personnel according to their needs, while on the other hand, companies can shape their employees in a very efficient way while at the beginning of their careers; this way companies can build a staff for their own needs and in accordance with the tasks they perform.Some differences were spotted in the size of the company (H3d).In this sense, large-and medium-sized companies give particular importance to the communication skills and knowledge of a foreign language, which is logical given the fact that these companies are mostly international companies with a large number of employees.Differences in skills according to the position were also identified (H3e).In this regard, the observations made in Section 4 can directly help companies to guide students and help in the formation of appropriate skills and knowledge with additional adjustments for special cases.
One of the best ways to retain talents is through adequate funding.The results of testing are fully consistent with previous research [15].The identified differences in talent funding between sectors are confirmed and described in more detail in Section 4 (H3f).The paid practice is one of the most common forms of practice in all segments.Mentoring as a type of practice is significant for contract logistics-3PL and trade companies.The reason is the relatively specific jobs and tasks that involve working directly with a mentor who is responsible for the transfer of knowledge and development control, which is in accordance with the Mura [55] who concluded that developed emotional skills contribute to improvement of interpersonal relations.Companies in the field of freight forwarding, international logistics and transport are interested in predefined practice programs with scholarships.Keeping in mind the trend of labor shortage, scholarships for talents during their studies are one of the best models of providing high quality and loyal staff.
The difference in viewpoint of practice by employees in different positions is explained in more detail in Section 4 (H3g); this is somewhat logical given that there are different requirements for skills and work methods in different positions; however, differences in the funding of students in different positions are not fully justified, since all students (trainees) should have the same scholarship.Given the lack of staff, companies will have to change their stance on this issue and start financing the students, regardless of company size, sector and position; otherwise, they will lose valuable personnel.

Conclusions
Economic changes, changes in the labor market, job dissatisfaction and fluctuation of labor in the logistics sector are recognized in the literature and practice.The research conducted in this paper is based on the analysis of the literature, but also on the situation in the logistics sector in Serbia.The basic goals and motives of the research were to perceive the current situation and to lay the ground for decision making and to solve the everpresent problem of employee fluctuation.The research findings lead to conclusions that are equally important to academic researchers as well as to practitioners.Eighteen hypotheses were developed and tested.A novelty of this paper is reflected in the fact that during the review of the literature a gap was established which refers to the development and testing of hypotheses (certain hypotheses that have been tested in this paper have not been tested so far) and which is to some extent filled by this paper.
The practical contribution of this paper is reflected in the fact that managers can increase employees' motivation and decrease labor fluctuation which is in accordance with previous researches [49,55,56].
Previous experience has been found to greatly affect job opportunities as well as position.The motives for changing jobs vary by sector.In manufacturing and trading companies, the inability for advancement is a major motive, while salary is the most common cause of job change in companies dealing with distribution and domestic transport and contract logistics-3PL.Changing salary and increasing promotion opportunities can directly affect the reduction of employee turnover which is in accordance with Ref. [57].Waiting time for the first job can be of great benefit to managers in small companies in order to shorten this time.The basic professional knowledge acquired at the faculty (especially at the Faculty of Transport and Traffic Engineering-University of Belgrade, Serbia) is an important basis for the successful completion of all logistics operations.Companies need to pay special attention to training as a particular form of employee satisfaction which is the same conclusion as in the research [58][59][60]; this can directly increase employee loyalty and reduce fluctuation.Regarding knowledge and skills, research has shown that knowledge of foreign language is especially important.Besides that, business communication skills are very important, which can help a lot in negotiating as well as time-limited tasks, which are the most common source of stress.Identifying and retaining talent through various forms of practice is of great importance for the logistics sector in Serbia, which is similar to the findings of Bavik and Wu [61,62].Particular attention must be paid to talent scholarships as an early form of employee training and recruitment.
The limitations of this research are the following.Firstly, this research is dedicated only to the faculty-educated labor, and not to the work-intensive labor (order pickers, drivers, etc.); labor fluctuation is even more present for these positions than the ones observed in this paper.The second one is relatively small sample observed in this paper.The third one is that this research did not take into account international labor fluctuation (when employee leaves Serbia in order to work abroad); only labor fluctuation associated with Serbian market was observed.
The research results represent an excellent foundation and assistance in human resource management for companies in the logistics sector in the region and beyond.Companies with appropriate actions can increase the satisfaction of existing employees, but also attract new employees.The most important thing is to create an appropriate environment in which the employee will want to work, improve and advance, but also to contribute to the development of the company.The research is the basis for future research in other countries and other markets.In future research, it would be desirable to focus not only on the faculty-educated labor (logisticians) but also on other much more numerous employees such as order pickers, drivers, etc.; it would also be good to compare the results obtained for the logistics sector of Serbia with the results of other countries, primarily in the region, but also more broadly, in order to obtain more relevant conclusions.Applying different quantitative approaches and methods for comparing (benchmarking) HR practices in different logistics systems is also an important future research direction.

Figure 1 .
Figure 1.Model of job satisfaction, labor fluctuation, education, knowledge and skills.