Paper ST01 Analysis of Dosage-Response Data in Agricultural Research

Agricultural researchers, especially research entomologists, are interested in determining how mortality rates change with increasing dose levels of a certain stimulus (e.g., pesticide, drug). A researcher may have a particular interest in determining the pesticide dose at which 50% (LD50), 75% (LD75), or 90% (LD90) of insect populations respond. Several procedures have been suggested for estimating the best dosage choice for an insecticide. When the response variable is binary or measured ordinally rather than continuously, PROBIT or LOGIT analyses based on Maximum Likelihood procedure are appropriate. This report will explore the use of several dose-response models including LOGISTIC, GENMOD, PROBIT, and CATMOD procedures of SAS/STAT which can all be used for statistical modeling of the dose-response data. All these methods predict the probability of a positive response (insect death) as a function of the pesticide dosage applied. Similar approaches have been widely used in many fields of research including medicine, laboratory animals research, economics, sociology, and genetics.