Double cross-validation of a test battery against multiple criterion variables found the first general factor accounts for most criterion variance in cross-validated regression weights. Small contributions are made by mechanical/technical and psychomotor factors. It appears a common general factor plays the major role in validity for a range of…

Item overlap coefficient (IOC) formulas are discussed, providing six warnings about their calculation and interpretation and some explanations of why item overlap influences the Minnesota Multiphasic Personality Inventory and the Millon Clinical Multiaxial Inventory factor structures. (SLD)