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ERIC Number: ED178614
Record Type: Non-Journal
Publication Date: 1979-Apr
Pages: 27
Abstractor: N/A
Reference Count: N/A
Getting Straight: Everything You Always Wanted to Know about the Title I Regression Model and Curvilinearity.
Echternacht, Gary; Swinton, Spencer
Title I evaluations using the RMC Model C design depend for their interpretation on the assumption that the regression of posttest on pretest is linear across the cut score level when there is no treatment; but there are many instances where nonlinearities may occur. If one applies the analysis of covariance, or model C analysis, large errors may result. Various methods are suggested for model C users to deal with non-linearities. One method is Mosteller and Tukey's re-expression of posttest scores. Another method depends upon differential weighting of scores in different parts of the pretest distribution. A third method uses quadratic regression lines and extrapolation to obtain a "no-treatment expectation." Still another method is to assume parallel regression lines for the treatment and control groups. A number of different logistic curves may be tried if both floor and ceiling effects are present. Graphing the scatterplot of pretest versus posttest scores is also recommended. (Author/CTM)
Publication Type: Speeches/Meeting Papers; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Identifiers - Laws, Policies, & Programs: Elementary and Secondary Education Act Title I