THE RELATIONSHIP BETWEEN ORGANIZATIONAL JUSTICE AND JOB INVOLVEMENT ON NURSE’S ORGANIZATIONAL CITIZENSHIP BEHAVIOR (EXAMINING THE MEDIATING ROLE OF ORGANIZATIONAL COMMITMENT)

This study aims to understand the role of organizational commitment in mediating the influence of organizational justice and job involvement on nurses’ organizational citizenship behavior. This explanatory research was conducted on the nurses of Universitas Muhammadiyah Malang Hospital (UMM Hospital). From the population of 127 nurses, 96 were selected as the sample through a proportionate random sampling method. The statistical analysis through Structural Equation Modelling found that organizational justice has no significant influence on organizational citizenship behavior, job involvement has a significant influence on organizational citizenship behavior, organizational commitment has a significant influence on organizational citizenship behavior, organizational justice has a significant influence on organizational citizenship behavior through organizational commitment, and job involvement has a significant influence on organizational citizenship behavior through organizational commitment.

In addition to being an important component in maintaining and increasing the competitiveness of companies, reliable and competent human resources are a support-ing factor in the health sector, such as hospitals. According to the recapitulation data obtained by the Indonesian Ministry of Health's Data and Information Center (2017), nurses are the health workers who occupy the highest number, namely 49% of the total employees in the hospital. This shows that nurses in the hospital environment have an important role; the better the nurse services, the better the quality of hospital services.
Universitas Muhammadiyah Malang Hospital (UMM Hospital), having 127 nurses with more than a one-year working period, is certainly not free from the demand to treat patients well. Its nurses as professional paramedics occupying the highest number of its employees can be considered as having good performance and competence. The increase in patient visits from year to year proves patients' satisfaction with nurse performance. However, Google's review shows there are some patients dissatisfied with the services provided and, surprisingly, there are also employees who feel dissatisfied in doing their jobs. That is, the employee disaffection that ultimately affects the service to patients, if not addressed, will immediately harm the organization. Because, sooner or later, it will reduce the performance of the nurses or employees concerned. The declining performance will certainly affect many things, such as nurses or employees will not be optimal anymore in doing their work or "extra" tasks or what we usually call organizational citizenship behavior (OCB).
OCB is very important since formal role job descriptions cannot cover all the behavioral arrangements needed to achieve organizational goals. In general, OCB contributes to organizational effectiveness by creating social capital and increasing efficiency and productivity (Somech & Oplatka, 2014).
Theoretically, many factors may cause OCB to be high in hospitals. Mahmoudi et al. (2017) said several variables affect OCB, including organizational justice. This is supported by researches conducted by Park andYoon (2009), Yaghoubi et al. (2012), and Mahmoud et al. (2016). However, different results were found in the studies of Sjahruddin et al. (2013) and Ade & Budiyono (2018)stating that there was no influence between organizational justice and OCB. This raises the research gap as an opportunity for conducting further researches. This research is therefore intended to examines the effects of organizational justice on OCB. We come up with the following hypotheses:

H 1 : Organizational justice influences OCB
According to Mahmoud (2017), job involvement is one of the factors that influence OCB. OCB and job involvement are interconnected with each another, where a nurse can identify his/her work, actively participate in it with a feeling of having high independence, all of which can spur feelings of selfesteem, responsibility, achievement, and goals in work (Lopez et al., 2016). This is in accordance with researches conducted by Chu et al. (2005), Mahmoud (2017), Kim, M.S (2013), Nwibere B.M (2014), and Salimi (2013, which stated that job involvement has a significant positive influence on OCB. However, these studies contradicted the results of other researches conducted by Sharagay & Tziner (2011) and Ade & Budiyono (2018), which stated that job involvement does not significantly influence OCB. This also creates a research gap as an opportunity for further research activities. Therefore, the second hypothesis is H 2 : Job involvement influences OCB The other factor that has a significant on OCB is organizational commitment. According to Fitria (2015), OCB is influenced by internal factors that come from within themselves, one of which is organizational commitment. The strong organizational commitment in individuals that occurs continuously will make them loyal to the organization because that is indeed the true desire in their hearts. (Titisari, 2014). The statement that organizational commitment influencing OCB is supported by research conducted by Fitria et al. (2015), Sjahruddin (2013), and Mahmoudi et al. (2017). On the other hand, organizational commitment can be an intervening variable, both between organizational justice and OCB and between job involvement and OCB. That is, the better the organizational justice and job involvement, the higher the organizational commitment so that it will ultimately have an impact on OCB. For this reason, the renewal in this research is the existence of the variable organizational commitment as the intervening variable.
This study aimed at developing a model to provide empirical results from the influences of organi-zational justice and job involvement on OCB. We investigated that organizational justice perceived by nurses and job involvement performed can influence OCB with the help of organizational commitment as a mediator. Specifically, the hypotheses that the researchers formulated were as follows: research. The population was all the 127 nurses who had been working for a 1-year period. The sampling technique used in this study was a proportional random sampling technique. The sample of this study was 96 nurses using the Slovin formula.
A five-point Likert scale, in the range of 1 (strongly disagree) to 5 (strongly agree) was employed in the data measurement. The Partial Least Square-Structural Equation Modeling (PLS-SEM) approach supported by Smart PLS (Hussein, 2015) was used for analyzing the data.

Characteristics of Respondents
Of the 96 questionnaires distributed at UMM Hospital, 96 were returned and considered to be used for data analysis, as shown in Table 1. Based on Table 1 above, based on the sexual characteristic, female nurses were more than men with a percentage of 59%. This shows that women were more interested in working as nurses. It is also known that the nurses were dominated by those aged 26-30 years, with a percentage of 75%. That is, most nurses at UMM Hospital were in productive age. Based on Table 1 above, it is known that the last education of respondents in this study was dominated by nurses with an Associate Degree, with a percentage of 55%, meaning that their potential for self-development, curiosity, and desire to try new things was still quite large. It was known that the working period of respondents in this study was dominated by nurses who had worked for 1-5 years, with a percentage of 94%, meaning that most nurses were still in the period of the introduction and development of their potential. The status of a nurse is dominated by permanent employees, with a presentation of 69%, showing that nurses at UMM Hospital had a greater sense of responsibility as permanent employees. The proportion of Poly Room nurses dominated with a percentage of 16%, indicating that the poly room has special attention because there are more patients there.

Outer Models
Outer Modelswereused to test validity and reliability. The indicators used in this study were reflective, so the Outer Models were evaluated using convergents validity, discriminant validity, and composite reliability. The criteria for each test are constructs that are declared reliable if AVE has a value greater than 0.5, the value of Cronbach's alpha is greater than 0.7, and the composite reliability value is greater than 0.7 (Uce Indahyanti, 2013). The re-sults of data analysis showed that the AVE valueis> 0.5, Cronbach's alphais> 07, and the composite reliability valueis> 0.7, the outer loading coefficient of each item concerning the latent variable is> 0.60, and the cross loading values of the items formed is greater than the value of cross loading in other constructs. These results indicate that all items are declared reliable in measuring latent variables and these variables have met the requirements of validity and reliability.

Structural Model (Inner Model)
The evaluation of structural models to evaluate the measurement of model provisions in the overall study was formed through several variables and their items. There are several approaches in evaluating structural models, including determinant coefficients (R-Square or R 2 ), Predictive Relevance (Q-Square or Q 2 ), and Goodness of Fit (GoF) (Uce Indahyanti, 2013). From the results of testing the structural models, the values of R 2 for the variable organizational commitment and OCB were 0.410 and 0.611, respectively. Meanwhile, Predictive Relevance (Q-Square or Q 2 ) was 0.77 (0<Q2<1), which means that the structural model in this study has a high predictive relevance (Uce Indahyanti, 2013). It can be concluded that the structural models of this study generally have high predictive properties, so hypothesis testing could be done.

Hypothesis Testing
The results of detailed hypothesis testing can be seen and explained in Table 2 below. In addition, the results of hypothesis testing obtained based on the PLS model can be explained in the following Figure 1. Based on Table 2 above, the results of testing each hypothesis in this study were obtained, which in general could be concluded that from all relationships between variables there is a positive and significant influence between one variable and another, except the relationship and influence between organizational justice (X1) and OCB (Y).

DISCUSSION Organizational Justice Influences Nurses' OCB
The hypothesis that organizational justice has a significant positive effect on OCB nurses is rejected. Given the coefficient is positive and not significant, it can be concluded that the existing organizational justice is less able to significantly increase nurses' OCB.
The result of this study, namely that organizational justice does not affect OCB, contrasts with several previous studies, such as those conducted by Park andYoon (2009), Sjahruddin (2013), and Mahmoudi et al. (2017) which said that there are a strong relationship and influence between organizational justice and OCB. It is also not in accor-

Job Involvement Affects Nurses' OCB
The hypothesis that job involvement has a positive influence on OCB is accepted. Given the coefficient is positive and significant, it can be concluded that the two are having the same direction. That is, the better the job involvement, the higher the nurse's OCB. This means that the job involvement of a nurse at Universitas Muhammadiyah Malang hospital can be said to be good. This is because the nurses who have been active in their work consider their work to be important so that when they are faced with work, they will always be serious in handling it.
The result, regarding the influence of job involvement on OCB, is in line with the results of researches conducted by Mahmoud (2017) (2013), who found a strong influence between job involvement with OCB. Another study that is in line with this finding is a study conducted by Cheng-I Chu et al. (2005) at one of the Taiwan hospitals with a sample of 314 nurses. The study stated that there is a significant influence on job involvement in OCB.

Organizational Commitment Ifluences Nurses' OCB
The hypothesis that states organizational commitment has a positive influence on OCB is accepted. Given that the coefficient has a positive sign, it can be concluded that the two are in the same direction. This means that the higher organizational commitment, the higher nurses' OCB.
The result of this study, namely that organizational commitment influences OCB, is in accordance with several previous studies, namely of Fitria et al. (2015), Sjahruddin (2013), and Mahmoudi et al. (2017), who have succeeded in conducting empirical tests on the relationship of organizational commitment and OCB. These studies also proved that there is a relationship between organizational commitment and OCB.
The other two hypotheses placed organizational commitment as a mediator. This study considered that mediation is a bridge to strengthen nurses'OCB.

Organizational Commitment Can Mediate The Relationship Between Organizational Justice and OCB
The hypothesis that states organizational commitment can mediate the relationship of organizational justice and OCB is accepted. Given the significant positive sign coefficient, it can be concluded that organizational commitment can play a role in increasing OCB indirectly. This result indicates that organizational commitment can be a predictor of the birth of OCB. Through high organizational commitment, organizational justice will affect nurses to work optimally.

Organizational Commitment Can Mediate The Relationship Between Job Involvement and OCB
The hypothesis which states organizational commitment can mediate the relationship of job involvement and OCB is accepted. Given the significant positive sign coefficient, it can be concluded that organizational commitment can play a role in increasing OCB indirectly. This indicates that organizational commitment is a predictor of the birth of OCB. Through the role of organizational commitment, nurses can be influenced to work optimally in teams.

Research Implications
This research contributes to conceptual development; the results of this study confirm previous studies that found the relationship between organizational justice, job involvement, organizational commitment, and OCB, both directly and indirectly. The results of this study are expected to provide implications in the form of insight and understanding for UMM Hospital in managing their human resources especially to increase their OCB.
Broadly speaking, a high OCB can be achieved by the high implications of organizational justice and job involvement to encourage nurses to be more optimal and maximal in working. Furthermore, OCB can also be encouraged by the high organizational commitment possessed such as the desire of strong nurses to maintain membership in the organization, which in turn will lead UMM Hospital to develop and continue to advance.

Research Limitations
This study still has limitations, namely its level of generalization is low because it was only done at UMM Hospital so that the results of this study can only be used as a basis for planning decisions at UMM Hospital alone.

CONCLUSIONS AND RECOMMENDA-TIONS Conclusion
From the discussion above, it can be concluded that organizational justice is unable to have a positive influence on OCB. This indicates that organizational justice cannot influence nor increase nurses' OCB, whereas job involvement and organizational commitment can influence OCB. This means that better job involvement and organizational commitment, then OCB will also continue to improve. Organizational commitment is also able to provide a role in the relationships of organizational justice with OCB and job involvement with OCB. This shows that organizational commitment can mediate the relationship between organizational justice with OCB and job involvement with OCB and can influence the strength of nurses' OCB.

Recommendation
Based on the results of the research described above, several suggestions need to be followed up, both for the development of knowledge for future researchers, especially in the field of human resource management, and for the interests of practitioners, especially at UMM Hospital.

Recommendations for Further Researchers
Further researches should be able to consider other factors that can influence OCB such as job satisfaction, employee morale, motivation, leadership style, organizational culture, etc. Further researches are also expected to be able to consider expanding the scope to strengthen the generalization of results in observed population objects.

Recommendations for UMM Hospital
UMM Hospital should continue to increase its nurses' OCB by increasing the variables organizational justice and job involvement, which are mediated by organizational commitment. This can be done by periodically evaluating the management system that has been implemented so far, whether it has been or not in accordance with the expectations of the nurses. Evaluation can be done by distributing questionnaires or through Google form that can be accessed easily. Through periodic evaluation, it is expected that UMM Hospital can strengthen the relationship between the organization and nurses with communication guidance that emphasizes relationships to find out issues related to organizational justice, job involvement, organizational commitment, OCB, and their assessment of the organization.