Use of log-linear analysis to construct explanatory models for TDBP- and AFB1-induced mutation spectra in lacI...

Mutation spectra recovered from lacI transgenic animals exposed in separate experiments to tris-(2,3-dibromopropyl)phosphate (TDBP) or aflatoxin B1 (AFB1) were examined using log-linear analysis. Log-linear analysis is a categorical procedure that analyses contingency table data. Expected contingency table cell counts are estimated by maximum likelihood as effects of main variables and variable interactions. Evaluation of hierarchical models of decreasing complexity indicates when significant explanatory power is lost by the sequential omission of interactions between variables. Use of this technique allows construction of the most parsimonious models to account for mutation spectra obtained in the two experiments. The resulting statistical models are consistent with previous analyses of these data and with biological explanations for causes of the observed spectra.