Recall that a sample should be an accurate representation of a population, because the total population may not be available.
An instrument that is externally valid helps obtain population generalizability, or the degree to which a sample represents the population.
The Home Environment Survey (HES) was developed to reflect availability, accessibility, parental role modelling, and parental policies related to PA resources, fruits and vegetables (F&V), and sugar sweetened drinks and snacks (SS).Parents of overweight children (n = 219) completed the HES and concurrent behavioural assessments.Few measures exist to measure the overall home environment for its ability to support physical activity (PA) and healthy eating in overweight children.The purpose of this study was to develop and test the reliability and validity of such a measure.Researchers chose which type of instrument, or instruments, to use based on the research question.
Examples are listed below: is the extent to which an instrument measures what it is supposed to measure and performs as it is designed to perform.There are numerous statistical tests and measures to assess the validity of quantitative instruments, which generally involves pilot testing.The remainder of this discussion focuses on external validity and content validity. Establishing eternal validity for an instrument, then, follows directly from sampling.This table is based on the work of Joanne Rich and Janet Schnall at the University of Washington Health Sciences Library.See their web site for much more information on finding research instruments.(the process of developing, testing, and using the device).