In most multi-campus studies of college impact that have been conducted over the past four decades, investigators have relied on ordinary least squares (OLS) regression as the analytic method of choice. Recently, however, some investigators have advocated the use of Hierarchical Linear Modeling (HLM), a method specifically designed for analyses…

First of a 2-part series concerned with: different types of inferential errors, single- vs. multi-institutional studies (MIS), longitudinal vs. cross-sectional data, statistical designs, measurement error effects, and measuring student-environment interaction effects. The best data is obtained from longitudinal MIS on student inputs and outputs,…

While any method of data collection is subject to certain unique types of systematic errors, the investigator has available several techniques for detecting such errors or for minimizing their effects on his conclusions. (Author/JB)