I have used the lme function in the nlme package to create a linear mixed effects model of data from a two-factor biological experiment, where both factors are categorical:
model<-lme(responsevariable~factor1*factor2, data=dataset)
I am trying to plot a quantile-quantile plot of this model to assess normality prior to performing an ANOVA on this model.
I have tried to use the qqnorm function:
qqnorm(model)
However, on executing the above command, I get the following error message:
"no applicable method for "xyplot" applied to an object of class "c("double", "numeric")""
I am looking for suggestions as to what this error means, if there is way to resolve it in order to get qqnorm to work on my model, or if not, what other functions could be used in R to create a quantile-quantile plot of my model.
