Probability of Grade by Class Size in Higher Education

I promised a colleague that I would locate the graphic above. It is one that I have carried in memory since 2005 and it may have the same effect on you. The source is The Effects of Class Size on Student Achievement in Higher Education, a 2005 paper by E. C. Kokkelenberg, Michael Dillon, and Sean M. Christy of Binghamton University (published by CHERI).

Even without a good key or great clarity here, you can make out the major finding from the Binghamton University researchers: probability of A/A- grades (at bottom of graph) is much higher in smaller college classes. When class size rises above 20, the highest grades settle into a narrower band that holds as the lecture hall fills to hundreds of students.

The researchers resisted naming cause, satisfied to report on nearly a million observations that cross disciplines at a northeastern university (highly selective research institution). The data are clear, holding for all variables, that grades and class size are negatively associated in higher ed.

Perhaps smaller class size really does produce more learning (assumes that grades reflect learning). Perhaps enrollment in small classes reflects self-selection by high achieving students. Perhaps professors like to give high grades to the students they spend more up-close time with.

One more link about grades and their use in university assessment efforts: Why Not Grades? on the web site of the Office of Institutional Research and Assessment at Old Dominion University.

Source published by the Cornell Higher Education Research Institute (CHERI), Cornell University:
Kokkelenberg, E. C., Dillon, M. & Christy, S. M. (2005) The effects of class size on student achievement in higher education (CHERI Working Paper #67). Retrieved November 3, 2008, from Cornell University, ILR School site: http://digitalcommons.ilr.cornell.edu/cheri/24/

© 2008 Mary Bold, PhD, CFLE. Email contact: bold[AT]marybold.com. The content of this blog or related web sites created by Mary Bold (www.marybold.com, www.boldproductions.com, College Intern Blog) is not under any circumstances to be regarded as legal or professional advice. Bold is the co-author of Reflections: Preparing for your Practicum or Internship, geared to college interns in the child, education, and family fields. She is a consultant and speaker on assessment, distance learning, and technology.