2.8. Data Management and Analysis
All data were double entered for consistency prior to analysis. An intention-to-treat analysis was employed. All statistical analyses were performed in SPSS for Windows. Changes in PSQI scores (primary outcome), ISI scores, subjective sleep parameters, and other questionnaire scores compared to baseline were examined using the GEE with repeated measures and dropout considered by including all available data points (intent-to-treat analysis). Groups and time points were fixed factors, and subjects were the random factor. Significant time-by-group interactions supported our hypothesis on the effects of FIR energy on sleep. Time and group interaction effect sizes were calculated based on the mean pre–post change in the treatment group minus the mean pre–post change in the control group divided by the pooled pretest standard deviation [