### Calculation of Course/Clerkship Raw Score, T-Score, T-Score Average, and Ranking Statistics

#### Course/clerkship raw score

A raw score is a numerical grade awarded in a pre-clinical course or a clerkship. Raw scores are not awarded for junior selectives, Special Topics, co-enrolled electives, Scholarly Activity, senior courses, and Medical Scientist Training Program courses. Raw scores are on a scale of 0-100 with 70=passing. The method for calculating a raw score is determined by the course/clerkship director, with the following restrictions:

• Raw scores are reported as integers. Scores less than 70 are truncated (e.g., 69.889=69), and scores 70 or higher are rounded up for decimal values of .5 or greater (e.g., 70.513=71, 71.488=71).
• If a student fails a pre-clinical course and is allowed to take a makeup test in order to pass, the raw score reported is the original (failing) score.
• If a clerkship student has to repeat the NBME Subject Exam, the score from the first attempt is used in calculating the clerkship raw score. If the student passes the second attempt, the calculated raw score based on the first NBME score is reported, even if it is below 70. If the student fails the second attempt, he/she fails the clerkship, and the clerkship raw score must be less than 70.  Thus, if the student fails the second attempt and the computed clerkship raw score is still 70 or greater, the reported raw score is set to 69.

#### Course/clerkship T-score

Course and clerkship raw scores are converted to T-scores to maintain comparability of scores across courses, years and curriculum changes.  A T-score is a commonly used standard score that indicates the position of a raw score relative to the mean of a group, expressed in standard deviation (SD) units.  A T-score of 50 corresponds to the group mean; a T-score of 60 is one SD above the group mean; a T-score of 40 is one SD below the mean, and so on.  A T-score distribution always has a mean of 50 and a SD of 10, regardless of the underlying mean and SD for raw scores, so each pre-clinical course and clerkship has a mean T-score of 50 and an SD of 10.  The formula for calculating a T-score is:

T-score = 50 + [10 x ((raw score – mean)/SD)]

The mean and SD for a pre-clinical course are based on students taking the course during the same offering (time period).  For clerkships, the mean and SD are based on active students applying for residency in the same year.

#### T-score Average (TSA)

A TSA is a weighted average of course/clerkship T-scores for a student during a given training phase.  Separate TSA’s are calculated for pre-clinical courses, clerkships, and overall.  The overall TSA is used for AOA nominations, honors, and for class rank reported in a student’s residency application.  If a student repeats a course or clerkship, both T-scores are included in the TSA.  Course/clerkship weights are determined by the Medical Education Committee.

The following example illustrates the calculations:

 Training Phase Course or Clerkship T-score Weight Weight xT-score TSA Pre-clinical Course 1 50 8 400 Course 2 65 4 260 Pre-clinical Sum = 12 660 55.0 Clerkship Clerkship 1 50 4 200 Clerkship 2 60 8 480 Clerkship Sum = 12 680 56.7 Overall Sum = 24 1340 55.8

The formula for TSA is [Sum of (Weight x T-score)] divided by [Sum of Weights].  Thus, Pre-clinical TSA = 660 / 12 = 55.0, Clerkship TSA = 680 / 12 = 56.7, and Overall TSA = 1340 / 24 = 55.8.  TSA’s are rounded to one decimal place.

#### Ranking statistics (percentiles and quartiles)

A percentile rank is calculated for T-scores in pre-clinical courses and clerkships and for each type of TSA.  For pre-clinical course T-scores, the “ranking population” consists of students taking the course during the same offering (time period).  For clerkship T-scores and for all TSA’s, the ranking population consists of active students applying for residency in the same year.

Percentile rank can be interpreted as the percent of students in the ranking population falling below a given T-score or TSA.  A T-score is considered to be the midpoint of a continuous score interval from 0.5 below to 0.5 above the score.  For example, a T-score of 55 represents the midpoint of an interval from 54.5 to 55.5.  Since TSA is reported to one decimal place, its interval is from .05 below to .05 above the TSA; e.g., a TSA of 57.5 represents the midpoint of an interval from 57.45 to 57.55.

To determine the percentile rank, we assume that one-half the scores (or TSA’s) in the interval fall below the midpoint and calculate the overall percent of students that fall below the midpoint of the interval.  Thus, the percentile rank for a T-score is the percent of students below the score plus one-half the percent of students at the score. For example, if 120 of 180 students scored below 55 and 11 of the 180 scored at 55, the percentile rank for 55 would be (120/180) + 0.5 x (11/180) = 66.6% + 3.1% = 69.7%.  Percentiles are reported as integers, rounding up for decimal values of .5 or greater, so 69.7 would be rounded up to 70.

Percentiles are converted to quartiles for reporting to students on the Academic Summary as follows:

 Quartile Description Percentile Ranks P1 Top 25% 75 - 99 P2 50 - 74 P3 25 – 49 P4 Lowest 25% 1 - 24