# Cross-Sectional Validation and Adaptation of the Stress Scale in Iranian Medical Students

## Description

Participants and data collection procedures The target population consisted of all third- and fourth-year medical students enrolled in Tehran universities in 2023, with a total number of 1880 based on the admission quotas of these universities (Table 1). The sample size was estimated based on the literature review on the minimum and maximum sample required for validation studies. Based on this, 100 students were selected for evaluating concurrent validity, 350 students for conducting exploratory factor analysis, 300 students for performing confirmatory factor analysis, and 150 students for assessing reliability (Sanjari & Soleimani, 2023). A proportional stratified sampling technique was employed for sampling. In this technique, a sample with a size proportional to the population size of each stratum was drawn from each university and each academic year. The sample size of each stratum was calculated using the following formula: n_i = (N_i)/(N)* n; where n_i is the sample size of stratum i, N_i is the population size of stratum i, N is the total population size, and n is the total sample size. Table 1 shows the number of samples for each university and each academic year by concurrent validity, exploratory factor analysis, confirmatory factor analysis, and reliability assessment. After visiting each university, the samples were randomly chosen from among the third- and fourth-year medical students. The inclusion criteria were being a volunteer, studying in medicine, studying in Tehran, and giving consent to participate. The exclusion criteria were having psychological, psychosocial, physical, or medical conditions related to stress; substance use; dissatisfaction; and incomplete completion of the questionnaire. Oral consent was obtained from the students and ethical considerations were explained. Confidentiality of data and the right to withdraw were assured to the participants. Out of 900 students who were invited to participate, 21 students declined to cooperate and 879 students completed the questionnaires. Demographic characteristics were recorded and collected.

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A proportional stratified sampling technique was employed for sampling. In this technique, a sample with a size proportional to the population size of each stratum was drawn from each university and each academic year. The sample size of each stratum was calculated using the following formula: n_i = (N_i)/(N)* n; where n_i is the sample size of stratum i, N_i is the population size of stratum i, N is the total population size, and n is the total sample size. Table 1 shows the number of samples for each university and each academic year by concurrent validity, exploratory factor analysis, confirmatory factor analysis, and reliability assessment. After visiting each university, the samples were randomly chosen from among the third- and fourth-year medical students. The inclusion criteria were being a volunteer, studying in medicine, studying in Tehran, and giving consent to participate. The exclusion criteria were having psychological, psychosocial, physical, or medical conditions related to stress; substance use; dissatisfaction; and incomplete completion of the questionnaire. Oral consent was obtained from the students and ethical considerations were explained. Confidentiality of data and the right to withdraw were assured to the participants. Out of 900 students who were invited to participate, 21 students declined to cooperate and 879 students completed the questionnaires. Demographic characteristics were recorded and collected.