CASE STUDIES IN BIOMETRY: Chapter 4. Measurement Error Models for Gypsy Moth Studies John P. Buonaccorsi The file ch4b.dat contains the defoliation data, with the following variables: 1. mdef = mean defoliation value obtained from 20 subplot values. 2. sedef = estimated standard error of mean defoliation obtained from 20 subplot values. 3. megg = mean estimated egg mass density obtained over 20 subplots 4. seegg = estimated standard error or mean egg mass density obtained from 20 subplot values. 5. cdefegg = estimated covariance of mean defoliation and mean egg mass density obtained from 20 subplot values. Sandy Liebhold has provided these data and given permission for its use in Case Studies in Biometry.