Abstract
The present study dealt with the antecedents of knowledge concealment with the aim of meta-analysis. This research, in terms of purpose, is descriptive, and in terms of the type of practical use, and in terms of the type of data, it is quantitative research. The statistical population of this research included domestic and foreign related individuals during the years 2016 to 2022, and 25 cases were included in the analysis process using a targeted non-random sampling method. Selected studies were analyzed using MAXQDA 20 software (to find effective factors) and CMA2 software (comprehensive meta-analysis software). Among the antecedents of knowledge hiding, 7 effect sizes are large (more than 0.5), 2 effect sizes are medium (between 0.3 and 0.5). In other words, leadership, organizational structure, knowledge ownership, technical knowledge, knowledge sharing perspective, psychological characteristics of employees, human resource management had the largest effect size. Also, among the antecedents of the relationship between knowledge concealment and competitive work environment, there were 5 large effect sizes, 2 medium effect sizes, and these factors including technology, organizational structure, micro factors, macro factors, and individual factors had the greatest effect. Also, among the antecedents of the relationship between knowledge concealment and organizational justice, there were 6 large effect sizes and 3 medium effect sizes, which include procedural justice, interactive justice, distributive justice, organizational commitment, challenges and diversity, open organizational systems. They had the most effect. In the end, it is suggested that the managers of the organizations provide the possibility of holding activities such as friendly gatherings outside the work environment, which leads to the increase of friendly relations and the reduction of interpersonal distrust.
Extended Abstract
Introduction
Today, knowledge is the most important asset and the biggest competitive advantage of many organizations. However, in today's highly variable organizations, the biggest and most complex problem of organizations is collecting and storing, retrieving, searching, distributing and retrieving knowledge. Exploitation of knowledge and intellectual property is a subject that is currently of interest to scientists. In order to achieve its goals, every organization uses a collection of knowledge that has been accumulated by each individual and in their minds. If these knowledges are not used, we can expect the failure of the organization or the high costs caused by the repetition of some decision-making processes and the lack of optimal use of experience and decision-making records. For this reason, leading organizations collect latent knowledge from personnel and work groups, which is called knowledge capital. In recent years, various organizations and companies have started joining the knowledge process, and new concepts such as knowledge work, knowledge work, knowledge management, and knowledge organizations indicate the intensification of this process. A knowledge organization achieves capabilities that can make a great power out of a small force. Such organizations are facing new challenges. Today, the competitive environment of organizations has become more complicated and changing. Continuous changes in knowledge have also created a new imbalance situation for organizations. The endless flow of knowledge has put markets in a constant state of change, which requires organizations to make continuous changes (Rahmi, 2015). Today, the capital of an organization is not only the financial and physical capital, but the knowledge capital of people is more important than the two and has been noticed by managers. In other words, human resource management is a complex aspect of knowledge management. In these organizations, knowledge management is used to optimize communication between employees and between high levels of management. Knowledge management in these organizations helps to create a culture of knowledge sharing among employees. Although knowledge can be acquired by individuals, but for it to be useful, it is necessary for all members of the group to participate in it. Knowledge is a concept beyond data and information. Knowledge refers to the collection of information, the practical solutions related to it, the results of its application in various decisions, the training related to it, the attitude of people in jobs and various responsibilities related to it. Each person's knowledge, even in a specific case, may be different from others. Knowledge is the basis of each person's skill, experience and expertise (Babaei Meybodi and Alirezaei, 2020). In the organization, knowledge is defined as what people know about their customers, products, processes, mistakes and organizational successes. Knowledge can exist in information bases, administrative departments or other internal and external sources of the organization. By all means, organizational knowledge is acquired over time and enables the organization to achieve a deeper understanding and lead its organizational formations with cleverness and intelligence, which are the characteristics of intelligence.
 
Theoretical foundations
In today's turbulent world, knowledge is the most important competitive advantage of organizations. This makes it necessary for organizations to take action to maintain and continue this competitive advantage. With the development of knowledge management and the increase of knowledge-based organizations, the change in the competitive environment of organizations has intensified and the environment of organizations is moving towards dynamism. Today, managers are eager to manage organizational knowledge so that they can benefit from its useful results. One of the necessary behaviors for knowledge management is the sharing of knowledge among the people of the organization, and this behavior occurs when a person has a desire to help others or learn from others in order to develop new capabilities in the organization. Since the organization cannot force its employees to share their knowledge with other employees and there is no compulsion, knowledge sharing will not happen until the individual wants to. The concept of hiding knowledge is as old as the topic of knowledge management itself. But it is a behavior that has been less researched. Identifying and explaining the effective factors on hiding knowledge is one of the solutions that can help the organization to move towards a knowledge-oriented and learning organization (Oliveira et al, 2018). According to the view of "knowledge is power", people usually hide knowledge so as not to lose their competitive advantage, and despite many researches in the field of knowledge sharing and the efforts of managers, organizations find it very difficult to achieve knowledge sharing. effective among their employees. Researchers have focused more on promoting the desired activities of the organization, especially knowledge sharing, and less attention has been paid to the reasons why people hide knowledge (Hosseinzadeh, and Miri, 2018).
Research Methodology
In terms of purpose, this research is applied, its nature is descriptive-analytical, and its method of implementation is meta-analysis, which is a systematic review and meta-analysis (Systematic Reviews and Meta-Analyses) that examines the meta-analysis of the antecedents of knowledge concealment. pay the statistical population of this research included domestic and foreign related individuals during the years 2016 to 2022, and 25 cases were entered into the analysis process using a non-random purposeful sampling method.
Research findings
The Q test was used to check the homogeneity of the studied studies and it can be claimed with 95% confidence that the null hypothesis that the studies are homogenous is rejected and the hypothesis of heterogeneity among the studies is confirmed. In order to avoid publication bias, the funnel diagram and safe N of error were used. The results showed that as the studies are drawn to the bottom of the funnel, their standard error will increase and their publication bias will increase. The results of linear regression show that at the 95% confidence level, the cut-off value is equal to 1.26935 and the test statistic is 0.58840. Since the value of p is one domain (p=0.42036) and two domains (p=0.81547), it means that the null hypothesis that the funnel plot is symmetrical and that there is no diffusion bias is confirmed. Rosenthal's safe-from-error (N) test shows the number of missing studies (with a mean effect equal to zero), which must be added to the analyzes to obtain statistical insignificance of the overall effect. Based on the results of the above table, it can be seen that 986 more studies need to be conducted and checked so that the p value of the two combined strains does not exceed 0.05, so 986 more studies must be done in order to reach the final results of calculations and analysis. If an error occurs, this indicates the high accuracy and accuracy of the information and results obtained in this research.
Conclusion and Discussion
The results of the meta-analysis of the reviewed studies showed that organizational justice, leadership style, organization design, competitive work environment and human resource management are effective on knowledge concealment in organizations, and this effect size in the reviewed studies is for combined effects. Fixed and random are equal to 0.629 and 0.603 respectively. The results of this research question, with the results of studies such as (Kamalipour et al, 2020), (Valikhani Dehaqani, and Mohammadi, 2022), (Babaei et al, 2020), (Manochehri et al, 2018), (Mehrabi Taleghani and Mohammadian Saravi, 2018), it is both side and straight. In explaining these findings, it can be said that hiding knowledge may be related to employees' fear of losing control and power over their knowledge. In addition, some employees try to protect their competitive advantage among colleagues, and since today knowledge is considered as a valuable asset and a strategic resource and capital, and providing services, quality and economic products without interest. Obtaining and managing this valuable resource is difficult and often impossible. Therefore, organizations need to be more productive from human capital, more efficient and effective learning of employees, satisfaction of customers and employees, prevention of repeating mistakes, reduction of rework, saving time, motivating creativity and innovation, etc. They should put knowledge in the center of their attention and manage it.