Steps 6, 7, and 8: Performing construct validity through exploratory factor analysis and confirmatory factor analysis
At first, exploratory factor analysis was performed to evaluate the construct validity of the Persian version of Justice Perception of Performance Appraisal. During exploratory factor analysis, Bartlett’s test of sphericity was used to justify the need for factor analysis, and also Varimax rotation was used to simplify and interpret the construct. Also, the eigenvalue method was applied to determine the number of components in the instrument. Furthermore, the adequacy of the sampling was evaluated through the Kaiser-Mayer-Olkin measure of sampling adequacy value. Bartlett’s test of sphericity was also utilized to determine whether the obtained correlation matrix has a significant difference with the value of 0 and if the application of factor analysis is justified accordingly. Also, SPSS version 17was used for exploratory factor analysis. Multivariate techniques were also used to perform confirmatory factor analysis to evaluate the relationships. The fitted model would be applied if the fit indices include the following conditions: a ratio of chi-square to the degree of freedom of below 3, the goodness-of-fit index (GFI) between -1 and 0, low or near 0 root mean square residual (RMR) index, the standardized root mean square residual (SRMR) index of below or equal to 0.08, root mean square error of approximation (RMSEA) index of below 0.06 to 0.08, three Bentler-Bont indices or normed fit index (NFI), Tucker-Lewis index or non-normed fit index (NNFI), and comparative fit index of above 0.95. Moreover, LISREL software version 8.8 was used for confirmatory factor analysis.
After obtaining the required permissions to conduct the research, the study participants were informed of the purpose and method of the study and were assured that the information would be kept confidential. Then, the data were collected after obtaining informed written consent and providing the necessary explanations on how to complete the questionnaire. Demographic information of the sample participants was collected using the demographic information form (age, sex, the latest educational degree, work experience, position, type of employment, and the name of the working ward).
All methods were carried out in accordance with relevant guidelines and regulations. This research has been done with the opinion of the ethics committee of Shahid Beheshti University of Medical Sciences in Tehran in 2017-2018. After the purposes of the study were explained to the participants, written informed consent was obtained from the participants who wished to participate in the study, and all the principles of confidentiality of information were observed.