Students with Grades on Both Grade Scales

We determined your class rank using a formula that combines your class ranks on courses you took on both the old grading system and the new grading system. To understand the method fully, you need to understand the statistical concept of a z-score. A z-score is a measure of how your performance compares to that of other students. It measures how many standard deviations your performance is from the performance of the student at the statistical mean of the class. A z-score therefore permits a sensible comparison of student performance on our two grading scales, even though they have different ranges and different distribution requirements.

We followed this process:

We took your cumulative GPA for all classes under the old scale and compared it to the cumulative GPA for other students for classes under that scale, generating your cumulative z-score for those classes. We call this your old z-score.
We multiplied your old z-score by a fraction to reflect the percentage of your graded units taken on the old grade scale. For example, if you had 60 graded credits on the old scale and 15 graded credits on the new scale, we multiplied your old z-score by 60/75. This yielded your weighted old z-score.
We followed the same process with your cumulative GPA under the new grade scale to generate a weighted new z-score.
We added your weighted old z-score with your weighted new z-score to yield a cumulative z-score. We ranked these z-scores for all students in the class, yielding your overall class rank.
This allowed us to rank students in a meaningful way, even with different numbers of credits on different grade scales. While it appears complex, this approach was needed to avoid misleading comparisons. For example, this method meant that a student did not end up with a higher class rank just because the student happened to take more classes than another student on the new grade curve with its more generous distribution requirements.

After re-ranking the class in this way, we assigned an imputed cumulative GPA that corresponds with each student's place in class on the new (4.33 maximum) scale. This gave us transcripts with grades on both scales that are fairly comparable to GPAs earned by students completely on the new grading scale. We entered the imputed GPA on the transcripts.

While we needed to calculate your class rank to engage in the process described above, your class rank may not be published. Only students in the top 20 percent of the class received a precise ordinal class rank on their transcripts.

We needed to engage in this exercise because we need:

To know class rank for purposes of graduation honors;
To provide the imputed cumulative GPA to help make your transcript comparable to other transcripts, both from USD and from other schools, that assign all grades on a letter-grade system; and
To publish the information about the imputed cumulative GPA reflecting class rank at the top 10 percent, top 20 percent, top third and top half of the class.

This process results in your class rank being derived from your cumulative z-score and not from your imputed cumulative GPA.

We will begin the entire process anew at the conclusion of each semester in which you are enrolled until you graduate; do not attempt to use this number as a basis for trying to calculate your own imputed cumulative GPA for any future grades you earn and do not be surprised if it appears much different in future terms.