The purpose of this study was to examine the extent to which the measures that make up each of the three separate accountability indices of school performance in South Carolina could be used to create an overall, reliable index of school performance. Data from public elementary, middle, and high schools in 2012/13 were used in confirmatory factor analysis models designed to estimate the relations between the measures under different specifications. Four different factor models were compared at each school level, beginning with a one-factor model and ending with a bi-factor model. Results from the study suggest that the measures which currently are combined into three separate indices of school performance can instead be combined into a single index of school performance using a bi-factor model. The reliability of the school performance general factor estimated by the bi-factor model ranged from 0.89 to 0.95. Using this alternative school performance rating, the study found that approximately 3 percent of elementary schools, 2 percent of middle schools, and 3 percent of high schools were observed to statistically outperform their predicted performance when accounting for the school's demographic characteristics. These schools, referred to as schools beating the odds, were found in most of the demographic profiles which represent South Carolina schools. The results of this study can inform decisions related to the development of new accountability indices in South Carolina and other states with similar models. The following are appended: (1) South Carolina's current school performance indices; and (2) Details on the analyses and results.
