Published online by Cambridge University Press: 31 May 2012
Regression equations of per cent defoliation of white birch stands, Betula papyrifera Marsh., to birch casebearer, Coleophora fuscedinella Zeller, eggs or larvae had precisions (standard error of the estimate, b) of about 20% of the estimate. Although log-transformation of counts stabilized the variance, it did not increase the precision of the equations. Precision of regression estimates based on data from whole-stratum sample units differed little from that from only four mid-crown branches. The latter sample universe is smaller and more rapidly examined.