Hi, to answer your original question I have a few suggestions. Your r^2 value is decent at 80% which tells you that 80% of the variation in the data can be explained by the relationship between the two variables. The other way that you can check if it's a good fit is to view a residual plot. Plot the residuals against the x's. There should be random scatter in this plot. Any patterns can tell you that the model isn't good to make predictions from. Not sure if this helps.