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.