real gmat vs manhattngmat practice tests

[irene_azzurra]

I scored in my last 3 gmat test
660
650
640

with the same scaled score on both verbal and quantitative sections
Should I expect the same result on the real test or should I expect great difference?!

thank you

[StaceyKoprince]

I assume you mean those were your scores on your practice tests? In general, IF you took the practice tests under official testing conditions (all timing, essays, length of breaks, etc), then you can assume that you will score in that same general range, though you should be aware that standardized tests have wide standard deviations.

For example, the official test has a standard deviation of about 30 points, which means that if a student could take the test twice in a very short period of time without any additional study in between, the student would have a 2/3 chance of scoring within +/- 30 points and a 1/3 chance of scoring outside of that range.

Our test has a standard deviation of about 50 points, as measured from a student's last practice test to that student's official test. This means that a student has a 2/3 chance of scoring within +/- 50 points and a 1/3 chance of scoring outside of that range. If we say your most recent practice test result was 660, then your most likely score will be in the range 610 to 710.

So, as a general rule, it is most likely that you will score within 50 points of your most recent practice test, assuming that the test was taken under complete official conditions and assuming that it hasn't been very long (>1 month) since that practice test. It is possible, though, to have a score that is outside of that range. If that happens, it is more common to experience a larger score drop than a larger score increase (perhaps because the person ran out of time, was not prepared for the stamina, got too nervous, etc).

[rahul9395]

Thanks for your information.

[StaceyKoprince]

you're welcome!

[JAgozzino2]

Stacey,

I have started practicing for the GMAT and have taken two MGMAT practice tests after being told to use MGMATs sentence correction guide (which I have only started reading, but is impressive and comes highly recommended). I have some questions about the critical reasoning on the MGMAT, particularly, I am interested in how those questions are crafted in your practice exams.

I received a near perfect score on the LSAT, I teach the LSAT and I find I am getting more critical reasoning questions wrong on the two MGMAT practice exams than 1. I ever did on the LSAT (which is supposedly significantly more difficult); and 2. I do when taking questions from the OG verbal review book.

One example of an incorrect question is the mold spore question I recently took on my CAT #2 (feel free to go into my profile to find the question, if instructors have that sort of access). The answer to this question is incorrect for a few distinct reasons. First, in order to be considered a necessary assumption, the negation of that assumption should make the argument invalid (i.e., the conclusion must not flow from the premises). If we negate answer choice A and write "mold itself does create moisture" the conclusion that a person *should* do something does not become invalid or incorrect. If A creates B, and we posit that B creates A, we have not, thereby, determined that A doesn't create B. Second, even without that logical error, the stimulus notes that mold is almost always found in places with substantial moisture so, even with other potential causes of mold and/or moisture, places in which substantial moisture would allocate, such as leaky faucets, *should* be targets. So the question is wrong for three reasons, two of which are major. First, A creating B need not preclude B from creating A. Second, a *should* statement does not require singularity of cause. Third, the use of "substantial moisture" in the stimulus, increases the validity of the conclusion in light of other possible causes for the problem.

Outside of the logical problems with the question there is also the fact that the "correct" answer choice is scientifically wrong. Mold requires moisture to grow. Positing a potential causal relationship that is scientifically incorrect is, while acceptable from a pure abstract logic perspective, something that would never be engaged in on any standardized test of merit.

This is only one question, but there have been a few where I've just been scratching my head trying to figure out how a conclusion flows from the premises.

Before I, or others, invest time attempting to discern problems in our critical reasoning skills as a result of taking practice exams, I was wondering what the process for creating these questions entails. Thanks.

[StaceyKoprince]

I trained to teach the LSAT last year and, when I took the first LSAT practice test I'd taken in a very long time, I got 6 CRs wrong. I figured out afterwards that this was because I tried to use GMAT techniques to answer them and LSAT CRs are something of a different beast.

Maybe about half of the question types are very similar on the two tests. The other half are anywhere from somewhat different to very different. (Some were different enough that something that would be considered outright wrong on the GMAT turned out to be the right answer for the LSAT.)

So I learned that using LSAT CR to study for GMAT or vice versa is not the best idea. Sometimes it works out fine but sometimes it leads you in the wrong direction.

In terms of how any of our questions are made, the questions are written by instructors who first go through a training process to be certified to write a particular type of question. The question formats are based on official questions. We do not, of course, simply re-write OG questions with a few different words or numbers - that's illegal. But we do our best to conform to the structures and principles underlying OG questions.

At the same time, the material isn't perfect, naturally. The official test writers have the luxury of sending problems through the "experimental" gauntlet, after which they can re-write or dump questions that didn't perform well. We don't have that capability. We do track a bunch of statistics after a question has gone "live" and, if the numbers come back wonky, we fix or dump the problem, but we can only tell after around 1,000 people have answered the question. (For what it's worth, I believe we're the only prep company that actually does this - checks after the fact based on the actual stats and fixes accordingly.)

So it's perfectly possible that you might find something that contains an error - and, if you do, please alert us. We want to know.

I also want to mention, though, that I've never taken an official GMAT (or worked through a set of official GMAT problems) on which I did NOT find some problem with which I felt I could very strongly argue (usually verbal, usually CR or RC). :)

As to the Mold Spore problem. I agree that the wording of the conclusion should be a bit different - something like: in order to ensure that there will be no mold poisoning, a homeowner should (etc).

As far as the issue of factual correctness of the answer choice on this problem - there are "factually incorrect" correct answers on the GMAT. The question is asking for the author's assumption. The author is often making a flawed argument with flawed assumptions. The flawed assumption may be flawed because it is factually incorrect or illogical in some way - but it is still the flawed assumption being made by the author of the argument and, therefore, the correct answer.

Beyond that, I agree that the general content of the argument should be as factually correct as we can make it. There was a problem in OG11 that dealt with patents and was factually wrong. Clearly, I had some specialized knowledge to know this, and the person writing the problem probably couldn't have been expected to have such specialized knowledge... nevertheless, the problem was actually factually wrong.

That doesn't excuse such a thing, of course - problems should still be as factually correct as we can possibly make them. But it does happen, even on the official test.

(I'm unclear, by the way, as to why you think choice A is factually incorrect. You mention that mold requires moisture, but the correct choice says merely that mold does not create moisture. Can you clarify? Thanks.)