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ERIC Number: ED343954
Record Type: Non-Journal
Publication Date: 1992-Apr-1
Pages: 6
Abstractor: N/A
Reference Count: N/A
Reliability of Growth Rate in the Longitudinal Measurement of Gain.
Woodruff, David; Houston, Mark
The growth curve approach to the measurement of gain of D. Rogosa, D. Brandt, and M. Zimowski (1982) was more fully developed by J. B. Willet and D. Rogosa (1985). Willet later (1989) discussed some practical aspects of applying a linear growth model and reached the conclusion that reliability may not always be a useful index for the measurement of gain. This paper presents a detailed derivation of Willet's reliability formula and shows that his conclusion concerning the effect of the time intervals on the reliability of the growth rate is, somewhat paradoxically, not completely correct. It is concluded that the reliability of the estimated growth rate parameter should not be accorded much attention; rather, attention should be focused on the standard deviations of the estimated growth model parameters and Willet's (1989) advice should be followed so as to decrease these standard deviations. Two examples are given. A 6-item list of references is included. (SLD)
Publication Type: Reports - Evaluative
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A