Quantitative Research Designs, Hierarchy of Evidence and Validity.

This paper provides a summary of the main quantitative research designs. Quantitative research designs occur in a hierarchy of evidence, ranging from descriptive research designs such as cross-sectional studies, and cohort designs, to more carefully constructed experimental designs like randomised control trials (RCT's). The quality of a study's findings is determined by factors affecting its internal validity and its application to other settings is gauged by its external validity.