The question is often asked: "what's a good value for R-squared?" Sometimes the
claim is even made: "a model is not useful unless its R-squared is at least x", where x
may be some fraction greater than 50%. By this standard, the model we fitted to the
differenced, deflated, and seasonally adjusted auto sales series is disappointing: its Rsquared
is less than 25%. So what IS a good value for R-squared? The correct answer
to this question is polite laughter followed by: "That depends!"