We select 100 people from the same representative population and ask who they will vote for. After conducting the survey, we collate their results and calculate the mean and standard deviation of voters over the five surveys. We pooled all our data and regress the potential factors using a stepwise regression model. We identified the following factors: gender, age, social networking activity (hours per day) social networking activity and in which state people reside.

After running the regression, we find an excellent fit, which suggests that the model is valid.

What remains to be checked before interpreting the results of results of this regression?