Beat The GMAT a GMAT & MBA community

1. I don't have to read any 'literature' to know that a mathematical theory works in practice only when its assumptions are met. The assumptions in the 'adaptive scoring' are that errors are indicative of the test-taker level and that there is a pristine correlation between a candidate abilities in different math sub-areas.

As a practicing tutor I know that BOTH assumptions are completely wrong: (1) smart test takers do make dumb mistakes quite often because GMAT is a rushed nerve wrecking exam and (2) ofthen there is no correlation between abilities in different math areas tested on GMAT.

So much about the 'nice theory of item response'. I guess the other tests like GRE, SAT, ACT have not read the item response theory too, cause they keep the old non-adaptive format.

2. You missed the point about the test with 92%. According to GMAT, 1 in 12 people will get a better score than that particular test I simmulated. I am aware what percentile means (thanks for the lecture though). I question that percentile truthfulness as a skill measure due to the way the score was obtained. My claim was that the test taker was penalized just because he made 2+2 errors in the begining, something that happens pretty often in real life, and was not given second chance later, while some of the 1 in 12 'better' test takers most probably made about 6-7 errors scattered around the middle and end of the test.

So my claim is, due to the skewed adaptive algorithm, test takers that tend to make errors earlier in the test are underestimated, in comparison to ones that don't. Now how probable is that to happen? From my experience, everybody underperforms in the begining and end of the test. How probable is that to happen in two questions in a row? As probable as two questions not in a row LOL

In that light, the old 'myth' that a test taker should be especially careful with the first 10 problems is actualy reallity.

In a real truthful test, covering all topics uniformly, with problems from lowest to highest difficulty in each topic, such problem would not arise. But who am I to argue with the 'item response theory', which is so much better for scoring because it is based on probabilistic assumptions that nobody has ever bothered to check. Yeah lets use likelihood instead of a simple old fashioned test, it's so much fancier LOL

3. I hope you aren't trying to tell me that YOUR posts are a useful yardsticks for a professional tone? Because to me they sound like a white noise and don't offer an actual scientific discussion of the facts presented but simply your condescending brain-washed opinion.

_________________
Skype / Chicago quant tutor in GMAT / GRE
http://gmat.tutorchicago.org/

Tutors who bang their heads against the wall figuring out a method to "game the game" instead of actually assisting students with quantitative and verbal strategies and fundamentals immediately lose all credibility in my eyes.

For some of us, the GMAT is actually a tool to help us get into our dream business schools, not some Rubik's cube for nerds to obsessively dissect as a hobby.

_________________
"Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it's the only thing that ever has" - Margaret Mead

Since experts are here, let me ask a question (stemmed from Ian's post saying "If the questions on which you guess are all very hard questions, that won't hurt your score much. If many of them are easy questions, that will hurt your score a lot. ")

For a student who typically score around 750, would the score be more negatively affected if he/she missed a easy question (say 500-600 level) or a hard question (say 700-800 level), assuming the question is not experimental?

My guess: if the student's overall performance is indicative of a 750 level, the CAT will treat an occasional mistake at a low-level question as an outlier, which does not count much. so missing a "on-level question" (a 700-800 level question) will be more severe. Just guessing....
If the answer is the opposite - missing easier questions weights more, then the implication may be that it's more important for a 750-level student to avoid silly mistakes on easier question than to instead take that extra proof-reading time to tackle hard questions.

I believe you experts have personal experience on this issue. Your insights are greatly appreciated.

Wow GMAC said it itself:
That was exactly what I was saying, despite the fact that some of the experts here were claiming that a string of false negatives is 'not very likely'. Notice GMAC did not say a string of false negatives is 'unlikely' like they said about a string of false positives.

Thulsy,

you should not worry about question difficulty on the exam BUT your should worry about it in your preparation. For some students, improving their score boils down to improving their accuracy (the ability to solve correctly a question at your level or below). Analyze your mistakes on GMATPret tests and see if you make silly errors on questions below your level and train strategies to avoid those.

Another thing you should know, that is not in the above quote, is that the scoring algorithm is more sensitive to a string of false negatives in the begining of the test when it is 'making its mind' about your level. That suggests that you should train to be especially careful and focused with the initial 10-15 questions on the test. That doesn't mean that you can do whatever you want at the end of the test, but be especially careful in the begining. A string of mistakes below your level in the begining will swing the scoring algorithm badly towards giving you lower level questions later and you won't be able to earn your true level score even if you answer those correctly.

I've shown that effect with GMATPrep tests, despite the fact that the experts here were claiming that this is not true and that it doesn't really occur in real life. Many people taking GMAT get scores quite lower than their practice scores with GMATPrep exactly because they have higher anxiety on the test day and they swing the scoring algorithm in the begining of each section towards lower scores with a string of careless errors below their true level.

_________________
Skype / Chicago quant tutor in GMAT / GRE
http://gmat.tutorchicago.org/