Andrew,

When they send you the scores, they also send you a sheet with an itemized breakdown of what topics you need to work on. If I'm not mistaken, each one of those bullets is a question that you missed. So, you can pretty much figure out the number of questions you answered correctly. Correlate that with your raw and scaled score, then you have one data point. If your buddies tell you what they got, then now you have more info to work with. However, if none of you Iowa guys/gals get in the 50th percentile, then you still don't know how many questions need to be answered correctly to get the mean per class year. That is the price you pay for being a bunch of geniuses.

But as you know, the percent correct correlated with each raw/scaled score will vary from year to year based on the difficulty of the exam.

What GlaucomaMD I believe was saying, is that you are overestimating the number of questions we need to get right in order to achieve the mean. To use your breakdown examples, you estimate that for second years, you need to answer 75-80% correct to achieve the mean. On last year's exam, if you answered 75% correctly, that would put you in the mid 80s percentile-wise.

Just my 2 cents....