Technical note: Application of the Box-Cox data transformation to animal science experiments.
In the use of ANOVA for hypothesis testing in animal science experiments, the assumption of homogeneity of errors often is violated because of scale effects and the nature of the measurements. We demonstrate a method for transforming data so that the assumptions of ANOVA are met (or violated to a lesser degree) and apply it in analysis of data from a physiology experiment. Our study examined whether melatonin implantation would affect progesterone secretion in cycling pony mares. Overall treatment variances were greater in the melatonin-treated group, and several common transformation procedures failed. Application of the Box-Cox transformation algorithm reduced the heterogeneity of error and permitted the assumption of equal variance to be met.
Peltier
M R
MR
Dept. of Dairy and Poult. Sci., University of Florida, Gainesville 32611, USA.
Wilcox
C J
CJ
Sharp
D C
DC
D000704:Analysis of Variance; D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D003627:Data Interpretation, Statistical; D015237:Dinoprost / Q000494:pharmacology; D004971:Estrus; D005260:Female; D006736:Horses; D010060:Ovulation; D011374:Progesterone / Q000097:blood; D015203:Reproducibility of Results; D012107:Research Design
D011374:Progesterone; D015237:Dinoprost