I'm trying to get a scatterplot graph showing 2 regression lines so that interaction effects are clear.
My code is as follows:
lm <- lm(Cage_Int ~ Sex + AVP_mvBNST_ros_caud + Sex:AVP_mvBNST_ros_caud, data=data)
plot(data$Cage_Int, data$AVP_mvBNST_ros_caud, xlab="V1aR in BNSTmv",
ylab="Interaction time", col=colors, pch=20)
curve(cbind(x,1,x,1*x) %*% coef(lm), add=TRUE, col="red")
curve(cbind(1,0,x,0*x) %*% coef(lm), add=TRUE, col="blue")
this gives me the right scatterplot graph,but the regression lines are not showing, which is not what I want (I want both regression lines to show, one for sex=0 and one for sex=1)
Thanks a lot in advance!
Run the regression with
sex=1 and create two separate linear models using
lm(). Once you define the two models
model1 = lm(<insert equation>) and
model2 = lm(<insert second equaiton>), you can simply ad a line using
abline() or, in this case:
after the plot function and that should do the trick. You can add colors and different line effects using
abline() as well.