Validity and Reliability: Part I

IN THE FIRST COLUMN OF THIS series, I discussed different types of research study designs (see September/October 2003 issue). In this column, I review the concepts of validity and reliability. Validity is a measure of accuracy and generalizability; reliability has to do with whether results can be repeated. Often these terms are used in reference to measurements or instruments. They can also be used to describe a study itself, however.¹ The overall validity of a study depends generally on the validity and reliability of the measurement tools, but other factors also contribute. This column focuses on overall study validity and reliability. Measurement validity and reliability will be the topic for a future column.