Research in the social and behavioral sciences often focuses on the measurement of unobservable, theoretical constructs such as ability, anxiety, depression, intelligence, and motivation. Constructs are identified by directly observable, manifest variables generally referred to as indicator variables (note that indicator, observed, and manifest variables are often used interchangeably). Indicator variables can take many forms, including individual items or one or more composite scores constructed across multiple items. Many indicators are available for measuring a construct, and each may differ in how reliably it measures the construct. The choice of which indicator to use is based largely on availability. Traditional statistical techniques using single indicator measurement, such as regression analysis and path analysis, assume the indicator variable to be an error-free measure of the particular ...