Shelf exams are standardized exams for each of the core clerkships prepared by the NBME. These are the people who make the USMLE, but the scores don't count or have anything to do with licensure. Medical schools like the shelf exams because they send them off to be graded, and then they get stats back about how well their medical students did relative to medical students across the country who also took the shelf exam at the same time. For this reason, our dean's office mandated that all of the core clerkships have to give the shelf exam. However, some of the clerkships already had their own "departmental" exam that they liked better than the shelf, and they didn't want to give it up, so they make us take their exam and the shelf exam, which really sucks.
How you are graded depends on your medical school and the clerkship. At my school, there is a standard form that all of the clerkships use to evaluate our subjective performance. The attendings/residents are given these forms and rate us 1-5 in areas like professionalism, history taking, problem solving, etc. There is also space for them to write comments about your performance. Then there are objective measures like the shelf exams. Some clerkships have other things like departmental exams, clinical competency exams, oral exams, presentations, writeups... How all of these are figured into your grade depends on who is running the clerkship. For example, our surgery rotation weights the shelf exam very heavily, whereas our family medicine clerkship only requires you to pass the shelf, and puts more weight on your evaluations from attendings and your performance on their departmental exam.
So all of this numerical data is combined to give you a grade which corresponds to honors, high pass, pass, fail. In addition, the clerkship director takes all of the comments written about you on your evaulations, and writes a summary paragraph about your performance. These paragraphs are cut and pasted, unedited, into your Dean's Letter when you apply for residencies. The nature of these paragraphs depends on the clerkship director. Some are very personal with a warm and fuzzy kinda feel, others are very dry, and just say stuff like you got this score on the shelf and performed above the expected level and saw 22 patients.
Hope this helps!
