Question: Multivariate Goodness-of-Fit test

Hello, I've recently started using maple 13. I am working on a project for school where I am attempting to use several independent variables to try to predict a single dependent variable. The nature of the project is that there is currently no known answer, and therefore I have been using regression analysis through maple on each individual independent variable on the dependent variable. I was difficult to find a way to preform a goodness of fit test on the data through maple, but I eventually saw a way on this site to compute the R^2 value. I am now seeking to perform the final stage of the analysis where I will be using all the independent variables to try to predict the dependent variable, and I am looking for a way to test the goodness of fit of the regression. If anyone knows of a way to accomplish this, I would be very grateful.  Data can be provided if necessary, though i am looking for the process and not just the answer as there may be some fiddling left to do in the project.