ERIC Number: ED234087
Record Type: Non-Journal
Publication Date: 1982-Mar-16
Reference Count: N/A
An Empirical Study of the Effects of Regression to the Mean.
Ingebo, George S.; Doherty, Victor W.
The Portland (Oregon) Public Schools undertook studies of regression based on a three-year data base of fall and spring test results in grades 3 through 8 in reading, language usage and mathematics. The objective of these regression studies was to determine the amount of correction for regression to the mean needed to accurately represent the growth from fall to spring of groups of students placed in treatment groups where fall test scores were a principal criterion in the placement of students in those treatment groups. A series of tables are presented to illustrate the findings. Regression patterns for reading, mathematics and language usage were found to be quite similar, although sufficient differences were found to recommend separate tabling of the correction factors for the respective subjects. Based on these results, it appears that statistical theory that shows error of measurement increasing symmetrically toward the low and high ends of a distribution of scores may not represent the reality of measurement error. (BW)
Publication Type: Reports - Research
Education Level: N/A
Authoring Institution: Portland Public Schools, OR.