The validation process of the scale includes the evaluation of internal consistency, content validity, sensitivity to change, test-retest reliability and the data will be analyzed according to the item response theory. In the cohort study, the association between HRQoL levels, mortality and progression-free survival will be measured in 250 patients with non-small cell lung cancer.
Analysis plan: Conventional methods of descriptive statistics will be applied in accordance with the characteristics of the variables. For validation procedures, exploratory and confirmatory factorial analysis techniques, estimation of correlation and internal consistency coefficients, and methods to compare means in repeated measures (ANOVA of repeated measures) will be used. In the cohort study, time-to-event models will be used (Cox proportional hazards models or parametric models, depending on the fulfillment of assumptions). Since the independent variable will have different times of measurement, time-to-event models will include methods that handle covariates that change over time.
