GMAT PREP of GMAC Score Erroneous -Bug in algo?

[pretzK233]

Dear All,

Stacey for your kind attention and analysis as well.

Urgency for analysis: I am at a critical stage of preparation with 1 month left for the exam. Each CAT is extremely important to further analyse my preparation. I took a CAT today from GMATPREP Exam 4.

Here's the snapshot of Quant result. I got a depressing 530 with Q39 and V23. I am usually at 600-620 range and this week was aiming for 650.

I may have taken about 10 GMATClub Tests and multiple CATs so far but never got only 'TWO' 700 level questions.
Number of Wrong strings - Only 2 of 3 strings
Number of Total correct vs wrong - 21/31 correct

Can you please advise on my performance and the correctness of this GMATPREP Test which supposedly the closest to the original one. Your input is VALUABLE to me!



1 PS 500 Correct 16 PS 500 Correct
2 DS 500 Correct 17 DS 600 Correct
3 PS 600 Correct 18 PS 500 Correct
4 DS 500 Correct 19 PS 500 Correct
5 PS 600 Wrong 20 DS 600 Correct
6 PS 600 Correct 21 PS 600 Wrong
7 PS 600 Correct 22 PS 700 Wrong
8 DS 500 Wrong 23 PS 500 Wrong
9 PS 500 Correct 24 PS 600 Correct
10 PS 500 Correct 25 DS 500 Correct
11 DS 500 Correct 26 PS 500 Correct
12 DS 600 Wrong 27 DS 600 Wrong
13 DS 500 Wrong 28 PS 500 Correct
14 DS 500 Wrong 29 DS 700 Correct
15 DS 600 Correct 30 PS 500 Wrong
31 PS 500 Correct


TOTAL Correct % correct
500 18 13 72%
600 11 7 64%
700 2 1 50%

[StaceyKoprince]

I'm sorry that you had a disappointing practice test experience. I know that's rough. Things don't always go in the right direction (in fact, things are often pretty up and down!). The only silver lining is that you can use this as a learning opportunity to help you figure out how to get better. (And that's a pretty good silver lining. )

The algorithm is basing your score progression on the level of difficulty of the questions that you get right and wrong, not just that you got some number of questions right or wrong. Missing lower-level questions therefore does more damage to your score—the lower the level, the more the damage.

The labeling by 500-600-700 is just a proxy, but it gives us a rough idea of the relative difficulty level of the questions.

I'm looking through the sequence that you've typed out and you did miss a number of questions labeled 500. In the first half of the test (through #15), you answered 4 600-levels correctly but you also missed 3 500-levels (and 2 600-levels). This is why you didn't get up into 700-levels in that first half.

You picked up a bit in the second half, especially that good string from question 15 to 20. But you also missed a couple more 500-levels, bringing your score down again.

Your task at this point is to go look at those 500-levels that you missed. What was going on there? Do you have some holes in your foundation? Did you make some careless mistakes? Do you need to work on certain strategies?

Also look at the other ones you missed—but start with the lower level ones. Then come back and tell me what you discovered.