I ran multiple regression with three predictor variables, which according to the theory I am using, should all predict the dependent variable.
However, one of the variable's partial plot shows what looks like a zero slope. The standardised coefficient is -.032 for this variable.
Below is the partial plot. Does it make sense to include this in the regression model? I was initially not going to include it on the grounds that it violates the assumption of linearity, but then I realised that there is some form of linear relationship, albeit a zero/horizontal slope.
This is m first project I have had to use statistics for, and I have no teaching in it at all, so have had to self-study so excuse any naivety.