MAS-I case studies
MAS-I · Put your knowledge to work in context.
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 case studies are 5 cases and about 3,915 words.
1Deductible Change in a Prior-Approval Rate Filing
Prairie Mutual writes personal auto liability in a single state. Its last filing produced 12.0 million of earned premium; incurred losses were 7.8 million and fixed underwriting expenses 2.4 million.
841 words, about 4 min2Overdispersion in Group Dental Claim Counts
A group dental carrier has 125 employer groups observed over four policy years, for 500 group-years of experience. The number of claims per group-year has sample mean 2.40 and sample variance 5.10.
707 words, about 4 min3Duration Gap on an Annuity Block
A life insurer's immediate-annuity block has a present value of liabilities of 95 million with a Macaulay duration of 12.0 years, measured at a flat 5% yield. Assets backing the block have a present value of 100 million and a Macaulay duration of 9.0 years.
741 words, about 4 min4Aggregate Loss VaR for a Homeowners Book
A homeowners writer has 50,000 policies in force. Claim frequency is modeled as Poisson with lambda = 0.08 per policy-year, so 4,000 claims are expected.
807 words, about 4 min5Borrowing Credibility for a New Territory
An insurer is entering a new state and has no credible experience of its own. It borrows a prior for claim frequency from a large, mature book in a neighbouring state: prior mean 0.09 claims per policy-year, prior standard deviation 0.03.
819 words, about 4 min