如何在从线性 model 创建的两个图中独立地 label 两个 x 轴？

Question

I apologize if this has been asked before, I'm sure there is a simple way to do this, but I have tried to search the forum and I can't find the answer.

We have created a linear model which takes a score on an administered test and examines it as a function of whether or not an individual is a native speaker of English and their year of study.

art_mod1A = lm(art_score ~ native + year, data = art, subset = abs(scale(resid(art_mod1)))<2.5)

Then we want to plot it out, using the allEffects function from the effects package.

plot(allEffects(art_mod1A), colors = "black", ylab = "ART Score", main = "")

This produces two plots in one image, like this.

What I don't see is a way to label the x-axes independently. Applying the same ylab to both works since they are illustrating the same score, but the x-axes must be unique. Specifically, "Nativeness" on the left and "Year of Study" on the right.

I thought perhaps I could use grid.arrange to put them together, as in this post , but it seems this is only for arranging multiple plots, which I can already do by nature of the model itself. This does not allow me to rename the axes independently.

Would anyone be able to point me in the right direction?

Thanks very much!

Answer 1

I figured it out. I will leave this up as a testament to my foolishness.

Basically I had to select the individual effects plots by using "selection=1" or "selection=2", then storing them as vectors. Then I had to put them back together using grid.arrange from the package (gridExtra), as per this thread.

So the code was like this:

artplot1 <- plot(allEffects(art_mod1A), selection=2, multiline= T, main = "", ylab = "ART Score", xlab = "Year of Study", colors = c("black", "darkgrey"), confint = list(style = "bars", 
                                                                                                                                                 alpha = 0.15))
artplot2 <- plot(allEffects(art_mod1A), selection=1, multiline= T, main = "", ylab = "ART Score", xlab = "Nativeness", colors = c("black", "darkgrey"), confint = list(style = "bars", alpha = 0.15))

library(gridExtra)
grid.arrange(artplot2, artplot1,  nrow=1,  ncol=2)

Thank you for your help!