Hedeker, Donald; Gibbons, Robert D.; Waternaux, Christine - In: Journal of Educational and Behavioral Statistics 24 (1999) 1, pp. 70-93
Formulas for estimating sample sizes are presented to provide specified levels of power for tests of significance from a longitudinal design allowing for subject attrition. These formulas are derived for a comparison of two groups in terms of single degree-of-freedom contrasts of population...