CAS Exam 5: Basic Techniques for Ratemaking and Reserving

Overview of Exam 5

CAS Exam 5 is the first exam in the CAS sequence that focuses specifically on property and casualty actuarial practice. While earlier exams test mathematical and statistical foundations, Exam 5 applies those foundations to the two core functions of a P&C actuary: ratemaking (setting insurance prices) and reserving (estimating unpaid claim liabilities). This exam bridges the gap between academic preparation and professional practice, and the material connects directly to the day-to-day work of most entry-level P&C actuaries.

Exam 5 is typically a four-hour exam with a mix of multiple choice and constructed response questions. The syllabus draws primarily from the Werner and Modlin ratemaking text and the Friedland reserving text, both of which are available through the CAS website. Many candidates find Exam 5 to be one of the more enjoyable CAS exams because the material is practical and directly applicable to their jobs.

Ratemaking Fundamentals

Exam 5 covers the fundamental techniques for developing insurance rates. The ratemaking process begins with collecting and organizing loss and premium data, then adjusting that data to make it suitable for rate analysis. Key adjustments include loss development (projecting immature losses to their ultimate values), loss trending (adjusting historical losses to reflect expected future cost levels), and on-leveling premium (adjusting historical premium to reflect the current rate level).

You will learn how to calculate indicated rate changes using both the loss ratio method and the pure premium method. The loss ratio method compares the projected loss ratio to the target loss ratio to determine the needed rate change. The pure premium method divides the projected losses by the exposure base to determine the indicated rate per unit of exposure. Both methods should produce the same indicated rate change when applied correctly, and understanding this equivalence is important for the exam.

Expense and Profit Loading

The exam tests your understanding of expense loading, profit provisions, and the overall ratemaking process from data collection through rate filing. Expenses in insurance include fixed expenses (which do not vary with premium) and variable expenses (which are proportional to premium). Understanding how each expense type enters the rate calculation is essential. The basic ratemaking formula incorporates the loss ratio, fixed expense per exposure, variable expense percentage, and profit and contingency loading to produce the indicated premium.

Experience rating and schedule rating concepts are also covered. Experience rating adjusts an individual insured's premium based on their own loss history, while schedule rating applies debits or credits based on subjective assessments of the insured's characteristics. Both techniques are used to modify class rates for individual accounts, and the exam tests your ability to calculate experience modification factors and understand the credibility weighting involved.

Reserving Fundamentals

The reserving portion covers methods for estimating unpaid claim liabilities. Reserves are one of the largest items on an insurer's balance sheet, and their accuracy directly affects the company's reported financial condition. Actuaries are responsible for ensuring that reserves are adequate to cover future payments on claims that have already occurred but have not yet been fully settled.

The chain-ladder (development) method is the most widely used reserving technique. It uses historical patterns of how claims develop over time to project immature accident years to their ultimate values. You must understand how to calculate age-to-age development factors from a loss triangle, select appropriate factors (using averages, weighted averages, or medians), and apply them to project ultimate losses. The assumptions underlying the chain-ladder method, particularly the assumption that future development patterns will resemble historical patterns, are important exam topics.

Alternative Reserving Methods

The Bornhuetter-Ferguson method combines the chain-ladder approach with an expected loss ratio estimate. It is particularly useful for immature accident years where the chain-ladder method may be unreliable due to limited development data. The formula is: ultimate losses = reported losses + expected unreported losses, where expected unreported losses = expected ultimate losses multiplied by the percentage of losses still unreported. Understanding when to prefer the Bornhuetter-Ferguson method over the chain-ladder method is a common exam question.

The expected loss ratio method simply multiplies earned premium by an expected loss ratio to estimate ultimate losses. This method is useful for very immature years or new lines of business where historical development data is not available. It relies entirely on the accuracy of the expected loss ratio assumption and ignores any actual loss experience, which is both its strength (stability) and its weakness (lack of responsiveness to emerging experience).

Practical Application

The exam emphasizes practical application. Given a data triangle, can you calculate development factors, project ultimate losses, and estimate reserves? You must be able to work through these calculations efficiently under time pressure. Practice building loss triangles, computing various types of factor averages, and applying different reserving methods to the same data. Being able to compare results across methods and explain why they differ demonstrates the professional judgment the exam is testing.

Focus on understanding the assumptions underlying each method and when those assumptions may be violated in practice. For example, the chain-ladder method assumes stable settlement patterns, but a change in claims handling practices or a shift in the mix of business can invalidate this assumption. The exam may present scenarios where you must identify that an assumption has been violated and recommend an appropriate alternative approach.

Study Tips for Exam 5

Read the source texts carefully, as exam questions often test specific details from the readings. Practice many numerical problems, especially building and completing loss triangles under timed conditions. Create formula sheets for the ratemaking and reserving formulas and review them daily during the final weeks of preparation. If you are currently working in a pricing or reserving role, leverage your job experience to build intuition for the material. Candidates who can connect the textbook concepts to their daily work consistently report better exam outcomes than those who study the material in isolation.