Why do GPAs go down?

<p>I’m not sure how credible this research is, but according to [National</a> Trends in Grade Inflation, American Colleges and Universities](<a href=“http://www.gradeinflation.com/]National”>http://www.gradeinflation.com/) , Chicago’s average GPA in 2006 was 3.35 with a severe upward trend. Compare with, say, Columbia at 3.42 in 2006, with a slight upward trend.</p>