Random sampling schemes satisfy the conditions for ignoring the selection mechanism in a model-based approach to inference in an observational study, such as a sample survey. In many studies ...

External validity refers to the generalization of research findings, either from a sample to a larger population or to settings and populations other than those studied. While definitions vary, ...

Study design: Measurement evaluation of the external and structural components of validity. Objectives: To examine the relationships between quality of life (QOL) as measured by the spinal cord injury ...