Comparing Harm Done by Mobility and Class Absence: Missing Students and Missing Data

This article addresses the relationship between academic achievement and the student characteristics of absence and mobility. Mobility is a measure of how often a student changes schools. Absence is how often a student misses class. Standardized test scores are used as proxies for academic achievement. A model for the full joint distribution of the parameters and the data, both missing and observed, is postulated. After priors are elicited, a Metropolis-Hastings algorithm within a Gibbs sampler is used to evaluate the posterior distributions of the model parameters for the Pittsburgh Public Schools. Results are given in two stages. First, mobility and absence are shown to have, with high probability, negative relationships with academic achievement. Second, the posterior for mobility is viewed in terms of the equivalent harm done by absence: changing schools at least once in the three year period, 1998–2000, has an impact on standardized tests administered in the spring of 2000 equivalent to being absent about 14 days in 1999–2000 or 32 days in 1998–1999.