Many observers have criticized the difficulty of the questions that appear in the OG (the Official Guide). The problem is not so much that the OG items are too easy as it is that the OG, like a traditional pencil and paper test, features items that range across the p scale. The high probability items (the easy questions) are generally of little interest to students who are seeking scaled scores at the far right tail. Suppose we group items into seven difficulty strata with the middle stratum called stratum x. The majority of items that one would encounter on a traditional pencil and paper test would come from the middle strata near x (i.e. x-1, x, x+1). In a traditional test, you would encounter very few questions at the top of the range (x+3) since these questions have undesirable characteristics for most test takers (it would provide low differentiation (discrimination) among low and medium ability test takers).

Now suppose we create an adaptive test from this body of traditional questions. The first test item administered to each student would come from the middle stratum (stratum x). If it is answered correctly, we move to stratum x+1 for the second question. If the first question is answered incorrectly, we move to stratum x-1 for the second question. If the first two questions are both correct, we move to stratum x+2. If this questions is answered incorrectly, we move back down to stratum x+1. At the end of the test we would combine the information concerning difficulty and number of questions answered correctly and incorrectly to obtain an estimate of the net number of items this student would have answered correctly on a traditional paper based test (this is the raw score). The estimated raw score on the paper test is then used to read the associated scaled score from the paper test's raw to scaled score conversion table.

Hjort

Did anyone find this overview helpful?

Hey Hjort, I did find your review helpful . However, I do not have any insights into it yet. Maybe soon enough...
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Best Regards,

Paul

Hjort's Empirical Score Estimator

(Vscaled score + Q scaled score)*7.35 + 70.3; (ROUND, -1)

This estimator is best suited for the 620-720 or so range which is probably of greatest interest to test takers here.

This predictor is purely empirical, it should not be construed as the product of theoretical derivation.

Hjort

There is a common argument that the GMAT is irrelevant to MBA admissions since schools can use so many other admissions factors in making their choices.

It is crucial to remember, however, that the GMAT has far more predictive power than most other admissions criteria. For instance, the median correlation of V,Q,andAWA scores with first year MBA grades was .42 while the median correlation of undergrad grades with first year MBA was only .25. When the GMAT and undergrad grades are combined the correlation increases to 0.47. Thus, assertions by schools that they weigh all admissions factors equally should be viewed skeptically (of course the correlation varies from school to school).

The median correlation for undergrad GPA and first year MBA is 0.25 as corrected above.

Hjort

By chance i happened to check these posts today only. Interesting findings. I would like to know how these studies were formulated. Are you referring to a simple regression on Grades versus say GMAT score? What were the partial regression coefficients. Were they significant?
What was the goodness of fit when you used all the variables - GMAT score, AWA, Grades, Work experience and salary.

I also had a feeling that work experience might infact have a negative correlation with Grades....
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To be or not to be....

Some readers (not many) might find the following information about GMAT scores interesting:

c. 1980 a score of 700 was the 99th percentile and the average score was only 462.

Historically, the total score was calculated from the sum of the raw scores of each section. The scaled score for V or Q was not used directly in the calculation of the total scaled score.

The subscores of the GMAT have exhibited some interesting trends. For instance, the mean for the Q section from 6/1994 through 3/1997 was 32 with an SD of 9. The mean for 1/2000 through the end of 2002 was 35 with an SD of 10. Thus, a score of 41 which was once one SD above the mean is now only about half an SD above. Comparing the same two periods the verbal subscore mean fell from 28 to 27 with the SD remaining at 9. At the same time, the mean for the AWA has increased from 3.8 to 4.0 while the SD increased from 0.9 to 1.0.

Is anybody still reading this thread? Is it still useful?

I extend a hearty thank you to jackson24nj for letting me know that people are still reading this interminable thread.

Hjort