ABSTRACT
Blanche has watched the wicked witches become heavier with each successive generation of laboratory colonization. During the first year of bioassays, Dr. Maven had her select and test insects within a very narrow weight range. But the insects’ weights have increased so much that the shelves supporting the insect colony are pulling away from the walls. Worse yet, Blanche simply cannot find enough insects in the weight range that she had been testing previously. She brings the matter to Paula’s attention. Dr. Maven ponders this situation-what should they do? They certainly cannot ask Weight Watchers for advice. Blanche might use a weight range with a higher upper limit, but how can Paula be sure that body weight does not affect responses of the insects to toxicants? After reading the material in yet another online literature search, Dr. Maven suspects that multiple probit or logit regression might be the most efficient method to handle this burdensome problem. As before, she has Blanche record a binary response (dead or alive). But now Blanche will also record dose and body weight as possible variables affecting response. This type of a bioassay is a binary quantal response experiment with multiple explanatory variables.
