ABSTRACT
Bioassays involving both time and dose as independent variables can have one of two possible designs. Separate groups of test subjects are treated with a given dose when the independent sampling design is used. With the independent sampling design, separate groups of test subjects are treated with a fixed dose. Each group is observed for a different period of time, and numbers of responses are recorded at each observation period. For the independent design, statistical models of time–response data for a fixed dose are straightforward. Time–dose (or time–concentration) relationships to mortality are of practical and theoretical importance in studies of pesticide activity on arthropods. The other alternative, the serial sampling design, involves treatment of each group of subjects with a given dose, treatment with use of several doses for the experiment as a whole, and recording of responses for each dose group at a series of times after treatment.
