Study and Strategy questions relating to the GMAT.
Everything OR Nothing
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Regrading your blog on GMAT scoring Algorithm

by Everything OR Nothing Wed Mar 25, 2015 12:59 am

Today I was reading the below blog and I got more confused.
Earlier I thought first few questions are as important as questions at any other part of the exam. But this blog seems to say below.Kindly clear me.Also let me know is the algo different in Quant from that of verbal section?

https://www.manhattanprep.com/gmat/blog ... our-score/

"This means that correct answers early in the exam move the steep part of the curve farther to the right than do later items. For example, if the item shown above were, say, the fourth item on an exam, a correct answer would probably move the steep part to a range corresponding to an overall score of 680 or 690. If this item appeared as the twenty-fifth question, a correct answer might move the steep part to a range corresponding to an overall score of “only” 660.

Why is this? Because by the time you have answered twenty-five questions, the CAT has gained significantly more information about your ability than after only four questions. Correct answers later in the exam will not cause the steep part of the curve to move as far to the right because the CAT is already zeroing in on your precise level. Earlier in the exam, the steep part moves farther because the exam is giving you the “benefit of the doubt.” That is, the CAT “thinks” to itself, “Because I do not know you, I was not expecting you to answer this item correctly, so perhaps your ability level is 70 points higher than I thought.” After twenty-five items (a somewhat arbitrary number), the CAT “thinks” to itself, “I have seen you answer twenty-five items, so the fact that you answered this item correctly makes a small difference in my assessment of your ability"
StaceyKoprince
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Re: Regrading your blog on GMAT scoring Algorithm

by StaceyKoprince Sat Mar 28, 2015 5:34 pm

This stuff is tough. "Moving the curve more" does not actually mean the same thing as "counts more toward your score."

I know it seems that way from the way that this is described - but this is only *one* part of how the overall algorithm works.

Essentially, earlier in the test, the algorithm has more "freedom" to decide what to give you next because it doesn't have a lot of data yet, so it can't make as precise decisions as it can later on, when it has more data.

However, there are other factors that go into the scoring to balance out the early weighting that seems to occur, so that in the end, each question ends up being worth roughly the same amount.*

*There are some exceptions to this. For instance, the couple of easiest and couple of hardest questions that someone gets in a single section are discounted a bit at the end because they are considered outliers.

Also, some of the other adjustments that are going on in the algorithm have more impact as your score goes higher. So while it may be accurate to say that, for someone scoring a 500, the earlier questions are marginally worth a bit more than the later ones, this is not true for someone scoring a 700.

In short, it's called an algorithm and not just a scoring scale for a reason. It's crazy complex. ;)
Stacey Koprince
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ManhattanPrep