The logistic analysis of categorical data from dental and oral experiments.

Logistic analysis methodology is being increasingly used in the analysis of categorical data from the biomedical sciences. We describe how the relationships between a dichotomous outcome variable and several qualitative classificatory or experimental variables can be modeled in a format similar to that used for quantitative data. The technique of weighted least squares is used to estimate the underlying parameters in the model and to perform various tests of statistical significance. The methodology is illustrated using data from a randomized dental anaesthetic study comparing three local anaesthetic solutions under two operative procedures. The similarities between the logistic analysis of dichotomous data and the analysis of variance applied to quantitative data are stressed.