# Gas station without pumps

## 2010 July 28

Filed under: Uncategorized — gasstationwithoutpumps @ 13:54
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The site www.gradeinflation.com has some fascinating statistics on grade inflation at US universities, spanning several decades.  One plot starts around 1920, showing GPAs of around 2.3 (C+), gradual growth in the 30s and 40s to 2.5, which held fairly steady through the 50s.  In the 60s there was explosive grade inflation, bringing public-college GPAs to around 2.8 and private-college GPAs to around 3.1.  Grades held fairly steady through the 70s and 80s, then started creeping up again.  By the 2006–07 school year, private-college GPAs averaged 3.30 (B+) and public-college GPAs 3.01 (B).  The variance is now quite high, with some schools having a GPA over 3.5 (A-)  and others having a GPA of 2.7 (B-).  It seems that there really are schools using the “A is average, B is bad, C is catastrophic” grading rubric.

As I have long believed, there is a major difference between humanities and sciences grading standards.  What I didn’t realize is that the gap is growing.  In the 40s, the average GPA in the humanities was about 0.17 points higher than in the sciences.  In the 00s it was around 0.3 points.  In some schools, the difference was more than 0.5 points.  I think that there is a gap between engineering and science also (with engineering faculty being stricter graders than science faculty), but I have no data to back up this belief.

The site also gives a rule of thumb for guessing the GPA of a college:

$\mbox{GPA} = 2.8 + \mbox{Rejection Percentage}/200 + \left\{ {0.2 \mbox{, if private}} \atop {0 \mbox{, if public}}\right.$

The site examines several conjectures about why there has been so much grade inflation. It manages to reject some of the hypotheses as inconsistent with the data, but does not claim to have a convincing explanation of the phenomenon.