ERIC Number: ED334207
Record Type: RIE
Publication Date: 1991-Apr
Reference Count: 0
Use of Observed, True, and Scale Variability in Combining Students' Scores in Grading.
Thayer, Jerome D.
Combining student scores to form subtotals and finally a total score to determine a grade is discussed. The composite score reached by combining measures or subtotals is only valid when the scores are combined so that the actual weight of each measure or subtotal in the total score is the same as the intended weight. Three types of variability should be considered in combining scores: (1) variability of true achievement (true variability); (2) variability that would exist if all possible levels of achievement had been measured (scale variability); and (3) variability of the observed scores (observed variability). Weighting procedures are summarized for teachers who want to use standard or converted scores and for those who want a simple weighting scheme or no weighting scheme. It is suggested that true variability and scale variability should be considered in addition to observed variability in weighting scores. If differences in true achievement cannot be ignored, one of the following options should be used: using a common scale for each measure; modifying possible points; and modifying scoring procedures. Sixteen tables provide illustrative examples. (SLD)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Authoring Institution: N/A
Identifiers: Composite Scores; Variability
Note: Paper presented at the Annual Meeting of the National Council on Measurement in Education (Chicago, IL, April 4-6, 1991).