Instrument selection for randomized controlled trials: why this and not that?
ABSTRACT A fundamental linchpin for obtaining rigorous findings in quantitative research involves the selection of survey instruments. Psychometric recommendations are available for the processes for scale development and testing and guidance for selection of established scales. These processes are necessary to address the validity link between the phenomena under investigation, the empirical measures and, ultimately, the theoretical ties between these and the world views of the participants. Detailed information is most often provided about study design and protocols, but far less frequently is a detailed theoretical explanation provided for why specific instruments are chosen. Guidance to inform choices is often difficult to find when scales are needed for specific cultural, ethnic, or racial groups. This paper details the rationale underlying instrument selection for measurement of the major processes (intervention, mediator and moderator variables, outcome variables) in an ongoing study of postpartum Latinas, Madres para la Salud [Mothers for Health]. The rationale underpinning our choices includes a discussion of alternatives, when appropriate. These exemplars may provide direction for other intervention researchers who are working with specific cultural, racial, or ethnic groups or for other investigators who are seeking to select the 'best' instrument. Thoughtful consideration of measurement and articulation of the rationale underlying our choices facilitates the maintenance of rigor within the study design and improves our ability to assess study outcomes.
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ABSTRACT: The accuracy of the Minnesota Leisure Time Physical Activity (LTPA) Questionnaire (a 1-year survey of non-occupational activity used in MRFIT) was studied in 78 men and women, age 20-59 years, by comparing survey results to the following measures obtained over a year's duration: six 48-hour physical activity records; fourteen 48-hour Caltrac accelerometer readings (Caltrac); 14 administrations of a 4-week version of the LTPA Questionnaire (FWH); 3 VO2peak determinations and percent body fat (% BF). The LTPA Questionnaire demonstrated: weak to moderate associations with % BF (r = -0.24) and with VO2peak (r = 0.47); a weak association with Caltrac readings expressed as MET.minutes.day-1 (r = 0.23); strong associations with corresponding activities reported on the FWH; and moderate associations with total and heavy activities reported in the physical activity record, but no associations with moderate and light activities. Furthermore, several types of LTPA were found to be either under-represented or not currently included in the Minnesota LTPA Questionnaire. It is concluded that although validation results were found to be quite good, several possible refinements were identified, which should improve the accuracy of the Minnesota LTPA Questionnaire in assessing habitual physical activity.Journal of Clinical Epidemiology 04/1994; 47(3):271-81. · 4.27 Impact Factor
Mycopathologia 02/2002; 153(1):1-3. · 1.65 Impact Factor