Method
The present study is methodological in nature. The study population
includes all the nurses working in the educational hospitals affiliated
with Shahid Beheshti University of Medical Sciences in Tehran, Iran. The
following inclusion criteria were taken into account for this study:
holding, at least, a bachelor’s degree in nursing as well as having more
than one year of related experience provided that these nurses had been
evaluated at least once a year and were willing to participate in the
study. The minimum acceptable sample size for factor analysis is
calculated according to the number of items given that 5 people are
considered necessary for each item (17). Since the instrument which was
used in this study includes 56 items, the minimum sample size was
calculated as 280 people; besides, considering the probability that 10%
of the participants may not answer the questionnaires, the ultimate
sample size in this study was estimated to include 300 people.
After correspondence with the developer of the instrument and obtaining
the required permissions, the translation and validation of the Justice
Perception of Performance Appraisal were performed according to the
instructions proposed by the University of Incarnate Word in the United
States. Therefore, the following 8 steps were taken for the translation
and psychometric analysis of the questionnaire:
1. Primary translation of the scale by a committee consisting of the
experts who were familiar with both Persian and English languages;
2. Evaluation of the translated instrument by the team members to reduce
the probable errors and mistakes in translation;
3. Preliminary research with 20 to 50 participants from the target
population to determine the stability (reliability) of the scale;
4. Application of the research scale to the entire target population;
5. Determining the internal consistency of the scale using Cronbach’s
alpha coefficient;
6. Application of exploratory factor analysis and determination of
factor loading for each of the subscales;
7. Elimination of the items with inappropriate Cronbach’s alpha
coefficient and low factor loading; and
8. Application of confirmatory Factor Analysis to determine the
construct validity of the scale.