Our research team has conducted numerous factor analyses over many years using data collected using the GOLD assessment system. These analyses have been conducted to both examine and confirm the underlying structure, or dimensionality, of the information provided by the items. These analyses have been conducted using nationally representative norm samples and have included children across the age range for which the measure is intended. These analyses have included four specific strategies: 1. Exploratory factor analyses (EFA) 2. Confirmatory Factor Analyses (CFA) 3. Measurement invariance studies (MI) 4. Principal Components Analyses of Residuals (PCAR) EFA is conducted to initially examine how the items tend to cluster together to measure one or more underlying dimensions. CFA is conducted to impose an existing structure on the items to determine if the theoretically derived factor structure as intended by the authors of an assessment can be supported by statistical evidence. MI studies are conducted to examine whether the underlying structure of an instrument varies over time or across sub-groups. PCAR is conducted to examine whether a given set of items measures a single underlying construct.