After a model has been fitted, it is important to analyze the residuals. We need to take some extra care because the data will belong to groups. Thus, we need to do a separate analysis for each group:
plot(model, resid(., scaled=TRUE) ~ fitted(.) | clientid, abline = 0)
The following output shows the fitted versus the residuals. These look good, and there is no obvious traces of structure here:
Then, type the following code:
plot(model, clientid ~ resid(., scaled=TRUE))
The following output shows the scaled residuals for each group:
In the previous two plots, we first showed the fitted-residual relationship; ideally, there ...
