Notes and Data Sources in Chapter 14 Logistic Regression

Chapter 14 Notes and Data Sources

4. This example is taken from a classic text written by a contemporary of R. A. Fisher, the person who developed many of the fundamental ideas of statistical inference that we use today. The reference is D. J. Finney, Probit Analysis, Cambridge University Press, 1947. Although not included in the analysis, it is important to note that the experiment included a control group that received no insecticide. No aphids died in this group. We have chosen to call the response “dead.” In Finney's book the category is described as “apparently dead, moribund, or so badly affected as to be unable to walk more than a few steps.” This is an early example of the need to make careful judgments when defining variables to be used in a statistical analysis. An insect that is “unable to walk more than a few steps” is unlikely to eat very much of a chrysanthemum plant!