Hello there, I am trying to run an ANOVA model using a non-Standard F ratio. Imagine that the treatments (treatments 1 & 2) are applied to the row not to individual samples. Thus the row is the experimental unit. Therefore my error term in my ANOVA table should be the error associated with with row. The question is how do I check the assumptions of an ANOVA model when I have a non-standard F ratio? For this type of model I would normally use plot(model) to examine the residuals. However this doesn't seem to work and I expect that R is looking for residuals that don't exist. Is there some option I can change on the plot command? Sorry if this is simple but searching for this answer was a little difficult as plot() has many uses. Below is an example. I am using R 2.10.1 and Ubuntu 9.04. Thanks in advance! Sam x <- runif(48, 2, 70) data <- data.frame(x) data$treat1 <- factor(c("ONE", "TWO", "THREE")) data$treat2 <- factor(c("PRUNED", "UNPRUNED")) data$row <- factor(1:12) model <- with(data, aov(x ~ treat1 + treat2 + treat1*treat2 + Error(row))) plot(model) Error in plot.window(...) : need finite 'xlim' values In addition: Warning messages: 1: In min(x) : no non-missing arguments to min; returning Inf 2: In max(x) : no non-missing arguments to max; returning -Inf 3: In min(x) : no non-missing arguments to min; returning Inf 4: In max(x) : no non-missing arguments to max; returning -Inf -- ***************************************************** Sam Albers Geography Program University of Northern British Columbia 3333 University Way Prince George, British Columbia Canada, V2N 4Z9 phone: 250 960-6777 ***************************************************** [[alternative HTML version deleted]]