This is more a statistics-related question and I request you kindly respond. I am trying to develop a regression model with time as one of the factors for a continuous dependent variable. There are three other independent variables in addition to time. After I run a linear regression using PROC REG with four independent variables and get the parameter estimates, can I use the predicted values for the dependent variable to draw curves in a plot of dependent variable versus time? Is it appropriate to just plot dependent var against time, when the equation was developed using other variables as well? Thank you.
You can do this, but you will have to fix the other independent variables to a certain value. When you plot dependent variable against time, you are plotting the main effect only. If there are interactions, this plot will not indicate interactions.