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Jan 11 2008

How can a shorter CBT MCAT be as effective as the longer paper MCAT?

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Author: Dr. James L Flowers
Category: MCAT Prep Tips

This is a very good question because the answer can tell you a lot about what to study and why.

AAMC spent considerable effort convincing the medical community that the paper based MCAT was a valid predictor of success in medical school: 
MCAT as Predictor of Success in Medical School

Why should we be convinced that the new CBT MCATs are equivalent to these old paper MCATs? Because AAMC has also spent a considerable amount of effort demonstrating the basis for their beliefs in a number of monographs and articles which are not as well known: 

  AAMC Monograph 1
  AAMC Monograph 2

These monographs explain how the MCAT conforms with Item Response Theory (IRT). IRT has become the standard for constructing tests like the MCAT:

  Wikipedia and IRT
  General IRT Comments I
  General IRT Comments II
  General IRT Comments III

To make the CBT equivalent to the old paper MCAT, the following steps are performed:

1)  Items are created and tested on a large number of individuals;

2)  Each item is described by an ICC (Item Characteristic Curve) based on the research;

3) Each item is further described by an IIF (Item Information Function);

4)  Any test is composed of the summation of individual items (and IIFs) and is characterized by the TIF;

5)  Any two tests will be equivalent if the TIF’s are equal regardless of the number of individual items.

So, what is the practicality of all of this for your taking of the MCAT? These are my “take it to the test” messages based on this analysis:

1)  Mock or simulated MCATs are useful if they have done the research and generated ICC’s, IIF’s and TIF’s. Since they do not, they are for the most part of much less value;

2)  If you want the best idea of how you will do on the real MCAT, take the practice MCATs (which were the “Real” MCATs at one time) under as close to real test conditions offered by AAMC at http://www.e-mcat.com.

See this prior Blog entry:

CBTs versus Paper MCAT

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