ETS, the test writers of GRE, provides students with a free diagnostic service that allows you to understand your post-test performance on the revised GRE general test. It is not well advertised and in my experience most students are not aware of this free service. In my experience, the majority of GRE test takers only take the test once and they may have little value to do post-mortem on their test. However, if you are planning on retaking the GRE test, this service may help you in understanding what may have happened during your test, so that you can on the relevant areas on your second attempt.
To access the diagnostic service, you will need to wait until you have received your official score report in the mail. You will need to enter the Registration number listed on the score report along with your test date and date of birth.
The diagnostic service provides the following information on the questions you encountered during the test: question type, difficulty level, time spent, and whether you got it right or wrong.
The images below are from the diagnostic report on the test I took in August 2010. The first section was fairly easy and had an average difficulty level of 3.2 on a scale of 1 to 5. The second section was fairly difficult with an average difficulty of 4. It is interesting to note that I received no Geometry questions in the second section. I don’t know how many questions one can miss in the quantitative section and still obtain a score of 170. My best guess would be a maximum of two questions, and would also depend on the difficulty level of the questions missed.
In the Verbal section, out of a total of 40 questions I missed 8 questions (scaled score of 164). Most of the questions that I missed are concentrated in the Reading Comprehension, an area that I would need to focus on if my goal is to raise my Verbal score.
Within each category below, questions are displayed in order of difficulty from 1 (easy) to 5 (hard).