Thursday, July 16, 2009

How to interpret USMLE scores

You will get the following info in your USMLE report :
your 3-digit score
your 2-digit score
Mean and Standard Deviation for recent US/Can registrants (not IMGs) - first time test takers.

This is a common misperception to call 2-digit score percent or percentile - 2 totally different things, by the way; it's neither percent, nor percentile!

From biostatistics you should know that percentile is the percent of people from total 100% who received scores lower than yours.

By using your 3-digit score, Mean and Standard Deviation and special statistical table, you can calculate your percentile, and by using your 2-digit score, you can calculate appr. percent of correctly answered questions.

USMLE Scores and Percentiles (simple guide)

2 digit scores are standardized so that the minimum passing score is a 75 and the maximum score is a 100. This approximately correlates to each digit between 75 and 100 being 4 percentiles of those who passed. The 2 digit score is something requested/required by state medical boards for all licensing exams so they can quickly evaluate the score without figuring out each exam's scales.

Scores used to be calculated after a group of students took them and you were given a 2 digit score, a 3 digit score, and a percentile. They used to do it where a large number of students took the exam, then they were all graded and statistics were calculated based upon all the students taking it then. The percentile was where you stood among the other students who took the exam in the block from which your exam was taken and scored. Therefore, each year, the median score would get a 50th percentile, although one year this could be a 205 and the next a 210. So a 240 in 1990 might be a lower percentile than a 235 in 1991. The problem is that a 240 is doing better, but 1991 may have been a "dumber" year so you could have a higher percentile with a lower score.

Now with computerized exams, they do not score your exam relative to the others taking it when you do... it is referenced to historical performance of the test items at which time a "difficulty level" for each item was assigned. This way, a 240 is a 240 no matter when you take it. Also, you do not have to wait for thousands of students to take the exam, do all your statistics, and then calculate the scores... you can calculate the score immediately. The implication of this, however, is that it is impossible to calculate a percentile since you are being scored against an inertia-laden grading curve. Every student could get a 240 now, and every student can fail.

There are many implications of this grading policy, and understanding it (really understanding it, not just saying that 240 is good and my score report says the mean was x with a sd of y) will serve you well.

Saturday, July 11, 2009

Goljan Audio Transcript - Pathology Lectures

This is something that you shall check. Goljan Pathology lectures now are accompanied with Audio Transcript. Full content of the audio transcribed in a concise document. 300+ pages of high quality transcript...

Couple of quotes:

"I like this!!! it was difficult for me to follow Prof. Goljan listening to audio lectures. Now I can read the transcript and focus on the areas I need. I put my favourite yellow and green labels on the most inportant pages... Thank you soooo much!"

"Great stuff - I downloaded goljan package in couple of hours and already started using audio transcript. This is fabuluous!"