Description Plots the mean (or other summary) of the response for two-way combinations of factors, thereby illustrating possible interactions. Usage interaction.plot(x.factor, trace.factor, response, fun = mean, type = c("l", "p", "b", "o", "c"), legend = TRUE, trace.label = deparse1(substitute(trace.factor)), fixed = FALSE, xlab = deparse1(substitute(x.factor)), ylab = ylabel, ylim = range(cells,