Introduction to instrument development: scaling methods

Deciding which instrument scale technique to choose is an important step in instrument development. Measurement theory dictates rules regarding level of measurement and approaches to decrease the error component of true scores. Measurement rules are applied to types of scaling, including methods to quantify demographic data, opinion rating scales, summated rating scales, semantic differential scales, and methods to quantify laboratory data. Consideration to scaling should be made before planning data analysis so that research questions or hypotheses can be answered using the appropriate statistical method.