u/Next-Wrongdoer9022

From the latest post-exam summary for Exam 8: “In one question, candidates were required to calculate the limited second moment of a lognormal distribution. This formula was inadvertently not included on the formula
sheet provided.”

This would have been caught if a single reviewer had attempted this question before it was put on the exam. Do people pre-test these exams at all? If so, how is it that a question which is practically unanswerable was able to make it on the exam without being caught?

Source: https://www.casact.org/exams-admissions/exam-results-summary-exam-statistics

Note: Exam 6I was excluded from the analysis due to thin data (and 99% of candidates will never take this exam)

These statistics are based on the summary of exam statistics excel file which provides pass rates for all exams offered by CAS since 1990. The three tabs of this file (Current Exam Structure, Joint Exams, and Historic 1990-2010) were considered separately, and the 5 lowest consecutive pair of pass rates by across all the exams in the CAS history are shown below.

#1. Exam 7 | F2025 & S2026 | Pass Rate = 27.4%

F2025 Pass Rate = 199 passes / 639 attempts = 31.1%
S2026 Pass Rate = 152 passes / 642 attempts = 23.7%

Total Pass Rate = (199+152)/(639+642) = 27.4%

#2. Exam 6CN | F2011 & F2012 | Pass Rate = 27.6%

F2011 Pass Rate = 38 passes / 155 attempts = 24.5%
F2012 Pass Rate = 56 passes / 185 attempts = 30.3%

Total Pass Rate = (38 + 56)/(155 + 185) = 27.6%

#3. Exam MAS-II | F2018 & S2019 | Pass Rate = 28.3%

F2018 Pass Rate = 11 passes / 40 attempts = 27.5%
S2019 Pass Rate = 17 passes / 59 attempts = 28.8%

Total Pass Rate = (11+17)/(40+59) = 28.3%

#4. Exam 1 (Jointly Administered) | S2000 & F2000 | Pass Rate = 28.4%

S2000 Pass Rate = 618 passes / 2667 attempts = 23.2%
F2000 Pass Rate = 857 passes / 2526 attempts = 33.9%

Total Pass Rate = (618+857)/(2667+2526)= 28.4%

#5. Exam 6US | F2011 & F2012 | Pass Rate = 28.5%

F2011 Pass Rate = 194 passes / 1002 attempts = 19.4%
F2012 Pass Rate = 407 passes / 1108 attempts = 36.7%

Total Pass Rate = (194+407)/(1002+1108) = 28.5%