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Putting values and axis X labels on the charts based on allEffects

2 messages · Dimitri Liakhovitski, John Fox

Dimitri Liakhovitski
# 
Dear everybody!
Need help with graphics. I am runnig a simple lm and then using
allEffects from 'effects' package:

require(effects)
model<-lm(Y~A+B, data=mydataframe)

I am trying to build (for each predictor - A and then B) a plot of means on Y.
I was successful doing it like this - in one swoop:

ml.eff<-allEffects(ml1, se=F)
plot(ml.eff,ylab="Title of Y")

Is it possible to show on my graph:
1. The actual Y values for each dot.
2. The title for A on the A graph and the title for B on the B graph -
but without having to do it one by one - because in reality I have
more predictors than one.

Thank you very much!
John Fox
# 
Dear Dimitri,
On
on
Just to be clear, what you're getting is a plot of predicted values of Y at
levels of A (or values of A, depending upon whether A is a factor or
numeric), holding B constant at its mean (or proportional distribution in
the data, depending upon whether B is numeric or a factor). Similarly for B
given A.
Yes, it's possible, but you'd have to make a custom graph to do it.
allEffects() returns a list of effect objects corresponding to the
high-order terms of the model (here A and B), each of which contains all of
the information you need to make the plot. To see what's there, try, e.g.,
str(ml.eff); to see the effect object for A, try str(m1.eff[["A"]]).
Do you mean more predictors than 2? In any event, to customize the main
title, you'd have to make the plots individually. You could automate this,
however, by a loop, looping over names(m1.eff).

More generally, the plot methods for effect objects try to behave reasonably
and to provide reasonable flexibility but aren't really meant to produce
publication-quality graphs.

I hope this helps,
 John
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