STUDY DESIGN: Meta-analysis. OBJECTIVES: To define the accuracy of clinical tests for assessing anterior cruciate ligament (ACL) ruptures. BACKGROUND: The cruciate ligaments, and especially the ACL, are among the most commonly injured structures of the knee. Given the increasing injury prevalence, there …

The subject of factor indeterminacy has a vast history in factor analysis (Guttman, 1955; Lederman, 1938; Wilson, 1928). It has lead to strong differences in opinion (Steiger, 1979). The current paper gives necessary and sufficient conditions for observability of factors in terms of the parameter matrices …