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ERIC Number: ED402340
Record Type: Non-Journal
Publication Date: 1996-Apr
Pages: 12
Abstractor: N/A
Reference Count: N/A
How Do Extreme Schools Change the Interpretation of Results in School Effectiveness Research? Effects of Outlying Second-Level Variables in HLM.
Sheehan, Janet K.; Han, Tianqi
This study examined the robustness of the estimation of fixed-effects in multilevel analysis, as might occur in the conduct of school-effects studies with outlying schools. Outlying values for both intercepts and slopes for individual schools were modeled separately to determine the effects of extreme values of second-level variables on the fixed-effect parameter estimation. A total of seven data sets were generated for the simulation. Under the conditions investigated in this study, adding a cluster of outlying schools had little effect on the estimation of gamma 10 and gamma 11. However, the standard error of gamma 01 increased, thereby increasing the conservativeness of the test of significance of gamma 01. This occurred for clusters of outlying slopes, intercepts, or a combination of both. Introducing a single outlying school also increased the standard error of gamma 01, the effects being more dramatic when the outlier was an extreme slope. (Author/SLD)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A