ABC | Volume 114, Nº5, May 2020

Original Article Silva et al. Florida Shock Anxiety Scale Arq Bras Cardiol. 2020; 114(5):764-772 Sample size Sample size determination for psychometric studies is usually calculated based on the number of items of the instrument. Some studies have demonstrated that a ratio of 20:1 or greater, that is, 20 participants per itemwould be ideal. However, ratios of 10:1 are sufficient to allow for adequate analysis. Thus, a minimum sample number of 150 patients was established. 25 Statistical Analysis Descriptive analysis Detailed descriptive analysis was performed, using measures of central tendency (mean, standard deviation, median, trimmed average, confidence intervals and interquartile interval). The Kolmogorov-Smirnov (KS) test was used to test the normality of each item in the questionnaire, whereas the Mardia test was employed to assess multivariate normality. All analyses were performed using SPSS 23 statistical package software and Factor 10.8.01, adopting a level of significance of 5%. Construct validity and dimensionality In this study, we conducted an exploratory factor analysis (EFA) and a confirmation factor analysis (CFA) to verify the dimensionality of the FSAS in its Portuguese version. The dimensionality testing was performed using Robust Parallel Analysis (RPA) through the Optimal implementation of Parallel Analysis (PA) with minimum rank factor analysis (MRFA), which minimizes the common variance of residuals. 27,28 The robustness of the test was determined Figure 1 – Cross-cultural adaptation process of the FSAS instrument 766