Five of the seven articles made reference to validity (for specific validity sources and methodologies, see Discussion), and three articles made reference to reliability (specifically through interrater agreement).
With reference to external validity, the extent to which the study results can be generalized is limited by the small sample size of patients with musculoskeletal diseases (241-COM, 164-NT) and their physicians (77-COM, 18-NT).
Among the strengths of the study are the similar catchment areas for cases and controls, the almost complete participation rate and the choice of hospitals controls, who are preferable to population ones with reference to reliability and validity of information on drug use, since cases and controls are similarly sensitised towards various aspects of their medical history (Kelly et al, 1990).
This was preferred with reference to the increased external validity this provides.
However, all schools were in rural northwest China, which limits external validity with reference to other populations.
Statistical analysis was performed to evaluate the reliability, the internal structure, internal consistency and concurrent criterion-related validity with reference to the gold standard questionnaire SF-12v2.
While we have used large surveys and treatment evaluation to assess SCI properties, more work is required to assess predictive validity with reference to independent clinical evaluation of insomnia disorder.
While comparisons with ISI cut-offs provide evidence of concurrent validity and indicate that an SCI score ≤16 may help detect probable insomnia disorder, studies of predictive validity with reference to independent clinical evaluation of insomnia disorder (the gold standard) are essential before firm conclusions can be made.
Previous research has shown the MARCA to have a same-day test-retest reliability of r = 0.84-0.92 for major outcome variables [sleep, moderate to vigorous physical activity (MVPA), physical activity level (PAL) and screen time (the number of minutes spent watching TV, playing videogames and using a computer)], and validity with reference to accelerometry of r = 0.45 for PAL [ 38].
Generally, as with construct validity, responsiveness is assessed by testing a priori hypotheses about the relationship of the changes in one measure to the changes in another (validated) measure, or with reference to a change in a gold standard (as with testing criterion validity).
