ETS Introduces Updated GMAT/GRE Score Comparison Tool

GMAT GRE Comparison ToolEducation Testing Service (ETS), the group that runs the GRE, has introduced an updated version of the GMAT/GRE score comparison tool that it first announced last year. It provides a slick, easy-to-use interface for applicants to input their GRE General Test scores and see a predicted equivalent total GMAT score.

The changes to the tool look mostly cosmetic, with a Flash-based interface replacing tables and charts, although it does look like ETS also increased the sample size on which the comparison tool is based. The 2009 version of included the results of 525 people who took both exams, while ETS says this version includes data from 893 test takers.

ETS has rolled out the enhanced comparison tool in its push to keep making inroads into the GMAT’s dominance as the admissions test of choice among top MBA programs. According to a press release put out by ETS to announce the enhanced comparison tool:

About 450 MBA programs worldwide now accept the GRE General Test, including almost half of the U.S. News & World Report’s top 100 U.S. programs and seven of the top 10 Financial Times’ global MBA programs, including the highly respected INSEAD, which recently announced it would accept GRE test scores. Because of the significant increase in the number of business schools accepting the GRE test, the yearly survey of business schools conducted by U.S. News & World Report for the first time collected GRE test data.

Back in 2009, GMAC fought back with its own statistical argument for why the first comparison tool’s large standard error of prediction made the tool useless (and even a bit misleading). We expect that GMAC will say the same thing this time around. Play with the new tool for a few minutes and you’ll notice the very wide predicted score ranges that the tool puts out. For example, input a score of 700 for each of the individual GRE General Test scores, and you’ll get a predicted GMAT score of 680. Not bad, right? But look at the predicted score range: 580 to 790! We’ve yet to meet an admissions officer who thinks that a 580 and a 790 are even remotely similar GMAT scores.

You might expect ETS’s response to be to keep growing the pool of test takers it surveys, to build a more and more robust model. But, even if they get to three times as many data points, those predicted score ranges may never be as tight as ETS would like. We say “may never” because we don’t have access to all of the data that ETS and GMAC see, but we would like to know more about this statement that ETS makes in the bottom half of the page, right below the comparison tool: “The two tests have a high correlation with each other.”

Those who are comfortable with statistics know that 893 is actually a pretty large sample size, and by that point your standard error of prediction should shrink a great deal (generating much narrower ranges of predicted scores, in the case of this tool) if there’s a tight correlation between the inputs and outputs. Said another way, if what ETS says about high correlation is true (and they’re not splitting hairs with terminology), then we’d expect that 893 data points would allow it to look at a 700/700 score on the GRE and predict a much narrower range of total GMAT scores. The fact that this isn’t happening with so much data makes us wonder just how much of a correlation there actually is between an applicant’s score on the GMAT and on the GRE General Test.

This will only get more interesting in the next 18 months, with ETS launching a revised GRE General Test in August, 2011, and GMAC introducing its new Integrated Reasoning section on the GMAT in June, 2012. Let the GMAT/GRE battle continue!

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