Are the shelf exam scores RAW scores of total # q's you got right?

[Arhat]

When people say they get 93 on medcine shelf, does this means the student got 93/100 q's right on exam. Or is there a formula to determine your score. It's insane how people can get above 90/100q's right when you have a huge arsh paragraoh to read to answer a friggin q's in one minute.

---

Members don't see this ad.

 

[tfom08]

I don't think it's #/100 just based on the fact that the average is 70 and the SD is 8 for all of the tests. It would be very difficult to produce multiple forms of a test and have that hold true in all cases.

 

[sunshinedoc]

I was actually wondering that too. I don't know how people could only miss seven questions on the medicine shelf, but who knows.

 

[DwyaneWade]

It depends. If they say a raw of 93, then they got 93/100. If they say a percentile of 93, well then it depends on how everyone else did.

 

[tfom08]

It depends. If they say a raw of 93, then they got 93/100. If they say a percentile of 93, well then it depends on how everyone else did.

So you think the NBME can make tests so that they know the median test taker will answer 70 questions correctly and the SD will be 8 questions? I just find it a little hard to believe. I think the "raw" score is actually scaled to make the median score 70.

 

[Alex05]

Think about it this way:

There are 100 questions,

The highest score you can get is a 99!

 

[Alex05]

Think about it this way:

There are 100 questions,

The highest score you can get is a 99!

 

[basupran]

I myself am a bit confused about this.

This is what I understand:
standard score: average is set at 70, sd is 8. To calculate percentile, simply divide the points above or below 70, divide by 8, and that is your z-score. Go here: http://www.measuringusability.com/pcalcz.php and click 1-sided.

percentile: calculated as above, or provided by NBME

raw score: number of questions right


Standard scores are basically to put all people on the same scale, much like the step 1. A 99 is not 99% of questions correct, nor is it 99th %ile (more like 88+ %ile). It is simply a standardized score.

 

[eachpeach]

Do all shelf exams have a mean of 70 and a standard deviation of 8? Or do different tests have different means?

I understand that the mean for that seating of the test be converted to a 70 and then raw scores corresponding to how your actual percent correct corresponds to the average percent correct for that seating. However, I was told that a raw score of 79 on a medicine shelf corresponded to a 73%, which wouldn't make sense if the mean was 70 and ST was 8.

 

[45408]

It depends. If they say a raw of 93, then they got 93/100. If they say a percentile of 93, well then it depends on how everyone else did.

I didn't think they'd release a raw score - just their scaled score - like Step 1, where you'll never know if you got 40% or 98% of the questions right.

 

[tfom08]

Do all shelf exams have a mean of 70 and a standard deviation of 8? Or do different tests have different means?

I understand that the mean for that seating of the test be converted to a 70 and then raw scores corresponding to how your actual percent correct corresponds to the average percent correct for that seating. However, I was told that a raw score of 79 on a medicine shelf corresponded to a 73%, which wouldn't make sense if the mean was 70 and ST was 8.

All NBME shelf exams have a median "raw score" of 70 and a SD of 8. That info can be found on their website. If someone quoted you those other numbers it is most likely your school's data and not the national data.

 

[eachpeach]

I e-mailed the score people at the NBME and this was the response:

"A scaled score is not a raw score. A scaled score is an equated score and as stated on the NBME website: 'For the clinical science disciplines, the subject examination scores are scaled to have a mean of 70 and a standard deviation of 8.'"

So I suppose if we hear a raw score, it indicates the percent correct (or at least its not the scaled score).