MAS-I study guide
MAS-I · Work through your exam, one topic at a time.
Exam MAS-I (Modern Actuarial Statistics I) is one of the examinations on the Casualty Actuarial Society's ACAS credentialing pathway. On the CAS website it appears among the 2026 ACAS exams, listed after Exams 1 and 2 and before Exam MAS-II, followed by the CAS DISCs, the Course on Professionalism, and Exams 5 and 6. It is aimed at candidates who have cleared the preliminary probability and financial mathematics exams and are now building the statistical foundation that later property and casualty work - ratemaking, reserving, and modeling - assumes. Expect a quantitative, computation-heavy sitting that rewards fluency with distributions, estimation, and model building rather than memorization. The MAS-I study guide has 4 sections and about 1,187 words.
01Insurance Principles and Regulation
Insurance transfers risk by pooling many exposures; the law of large numbers makes the pool's average loss far more predictable than any single loss. A candidate must be able to define risk transfer versus risk retention, insurable interest, indemnity, subrogation, and utmost good faith.
314 words, about 2 min02Probability and Statistics
Master the frequency family (binomial, Poisson, negative binomial) and the severity family (exponential, gamma, lognormal, Pareto). Be able to produce means, variances, and moment generating functions on demand, and to recognize a distribution from its mgf or variance-to-mean ratio.
273 words, about 1 min03Financial Mathematics
Convert fluently among effective interest i, nominal i^(m), discount rate d, and force of interest δ, using (1+i) = (1 + i^(m)/m)^m = e^δ and v = 1/(1+i). Note that d = i/(1+i) = 1 − v, a relation that shortcuts many annuity problems.
289 words, about 1 min04Actuarial Models
For S = Σ X i with random claim count N, use E[S] = E[N]·E[X] and Var(S) = E[N]·Var(X) + Var(N)·(E[X])². Independence between N and the X i is required.
311 words, about 2 min