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Comparisons Over Time
Calculation differences between CU-Boulder and CU System
Comparison with analyses by the CU System. Peer comparisons can
be done by different methods. Due to differences in data available to CU-Boulder (in Planning, Budget, and
Analysis), we typically calculate average salary and compensation figures while
CU system officials calculate weighted averages. The story is the same in both cases but the precise numbers differ in
the two sets of results.
Here we call the two sets the "PBA results" (for Planning, Budget, and
Analysis) and "system results" (for CU system). Here's why they vary.
- Peer institutions included
- In PBA results, 2001-02 and later data consists of all non-union AAU public
institutions including Texas A&M and SUNY-Stony Brook. Calculations for 2000-01 and earlier exclude Texas A&M and SUNY-Stony Brook.
PBA is working with Texas A&M and SUNY-Stony Brook to collect salary and total compensation data for years prior to 2001-02.
- System results do not include data for Texas A&M and SUNY-Stony Brook for all years prior to 2004-05.
- Data differences
- System results include UCB figures whereas CU-Boulder generated graphs exclude CU-Boulder figures.
- Data precision is different since system calculations use exact averages for each institution, while the CU-Boulder graphs
include figures published by AAUP, which are rounded to the nearest $100 by institution.
- The way the peer average is calculated.
- Averages are always within rank, within year, in both methods
- Consider a case with just two peer institutions
- A: salary $50,000, N of faculty at that rank 100
- B: salary $80,000, N of faculty at that rank 200
- PBA calculates a straight average: $50,000+$80,000 / 2 = $130,000/2 = $65,000.
This method captures the salary at the "average institution"
- System uses an average calculated by AAUP, which weights by N
of faculty at that rank. ((100*50,000) + (200*80,000)) / 300 = 210,000/3 = $70,000.
This method captures the "average of all faculty in peer institutions"
in the specified rank.
- Institutions with higher salaries in each rank tend to have higher
proportions of their faculty at higher ranks (e.g., Berkeley is
over 65% full profs). Therefore the system/weighted method produces
relatively higher peer averages at higher ranks, lower at lower
ranks, than the PBA unweighted method.
- PBA's analyses of salaries by college and discipline also use
unweighted averages.
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