Jordan Rickles

Examining Heterogeneity in the Effect of Taking Algebra in Eighth Grade

ABSTRACT Increased access to algebra was a focal point of the National Mathematics Advisory Panels 2008 report on improving mathematics learning in the United States. Past research found positive effects for early access to algebra, but the focus on average effects may mask important variation across student subgroups. The author addresses whether these positive effects hold up when the analysis is expanded to examine effect heterogeneity. Using a nationally representative sample of eighth-grade students in 1988, the author examined sensitivity of findings to methods for selection bias adjustment, heterogeneity across the propensity to take algebra in Grade 8, and across schools. The findings support past research regarding positive benefits to Grade 8 algebra and are consistent with policies that increase access to algebra in middle school.

Using interviews to understand the assignment mechanism in a nonexperimental study: the case of eighth grade algebra.

Many inquiries regarding the causal effects of policies or programs are based on research designs where the treatment assignment process is unknown, and thus valid inferences depend on tenuous assumptions about the assignment mechanism. This article draws attention to the importance of understanding the assignment mechanism in policy and program evaluation studies, and illustrates how information collected through interviews can develop a richer understanding of the assignment mechanism. Focusing on the issue of student assignment to algebra in 8th grade, I show how a preliminary data collection effort aimed at understanding the assignment mechanism is particularly beneficial in multisite observational studies in education. The findings, based on ten interviews and administrative data from a large school district, draw attention to the often ignored heterogeneity in the assignment mechanism across schools. These findings likely extend beyond the current research project in question to related educational policy issues such as ability grouping, tracking, differential course taking, and curricular intensity, as well as other social programs in which the assignment mechanism can differ across sites.