i am not a gmac rep, but i have read a fair amount of the literature in this field and know a good bit about this stuff.
tutorphd wrote:Personally, without reading the mathematical mumbo-jumbo, I know that the algorithm takes certain probabilistic assumptions to function and even if these assumptions are correct for a given test taker, it is NOT possible to estimate correctly the test taker abilities only with 37 questions on limited topics with scant number of questions on each topic.
au contraire, the adaptive algorithm gives results with pretty impressive fidelity after far fewer than 37 questions. the only reason to have so many problems is, essentially, "noise reduction".
if you are a tutor, you should know this firsthand, anyway. when i'm gauging a student's quant ability, i can get a pretty good idea of where he/she stands after only about 3 or 4 problems, and i can pretty much predict exactly how he/she is going to perform, and where the difficulties are going to be, after at most 10 problems.
... and the algorithm is a lot smarter than i am.
also, keep in mind that only about 27, not 37, problems are actually used in scoring the test. you are forgetting about the rather substantial number of experimental questions on the exam.
I've seen papers in physics with a textbook correct statistics producing wrong results because they were based on wrong or too idealized statistical premises.
this test produces results with pretty impressive reproducibility and consistency, so the bulk of the evidence is on gmac's side of the argument.
I remember vaguely I've read somewhere that the algorithm was more biased on the initial questions and that is why the prep companies advised in the past to do the initial questions slower and more carefully.
GRE, mid '90's. that was when adaptive testing was in its infancy. it has progressed considerably since then, to the point where that version (almost twenty years old!) is virtually unrecognizable. kind of like, say, cell phones, or wireless internet, or any other technology that has been constantly evolving.
Since then, I think the 'infallible' algorithm was 'corrected' lol
no one of any significance has ever treated the test as infallible. (hence, among other things, the possibility of retaking the test.) however, when it comes to evaluating test-takers with vastly divergent ability levels, it's pretty much the best option out there at the moment. or, at least, the
least bad option, depending on how you look at things.
in any case ... your argument here seems to be "the algorithm isn't perfect", which isn't actually an argument at all.
other than that, i'm not really following your point. so, if you have a more specific thesis here, you should articulate it, in a way that "fits on a business card". otherwise, it just seems as though you're basically coming onto gmac's own turf (= this folder) for the sole purpose of throwing obloquy at gmac. that isn't going to help anybody.
I am toying with an idea to go to GMATFocus and answer every second question in quant randomly to see if my final score will drop significantly. I wonder if anyone has done that and is it possible to get almost the same score with half the effort?
assuming you mean GMATPrep and not GMATFocus, this has been done hundreds of times, without any sort of revolutionary game-changing result.
however, this is investigative science, so a larger data set would always be nice.
if you're familiar with most the problems (and lazy enough to google up the answers to the ones you don't know), it will take you all of 15 minutes to go through the test and try this. so do it!
if you find anything significant, post it, for the edification of anyone and everyone.
