Interactions in entomology: Multiple comparisons and statistical interactions in entomological experimentation

Research reports published in agricultural journals indicate that in many situations the use of multiple comparison procedures has been either inappropriate or not the most meaningful method of analyzing the data. When the interaction is absent, only main effects should be reported in scientific journals, with some assurance that the effect of one factor holds at all levels of the other factor. However, when interaction is present, more detailed analyses and sometimes plotting the means for each of the cells may be very helpful in understanding the results. Multiple comparisons, main effects, and interactions are discussed using entomological examples to present a more meaningful and understandable explanation of statistical techniques to those researchers who conduct experiments in which each level of one factor occurs in combination with each level of another factor. Analysis of variance, contrasts, and fixed and random effects are also discussed.