On-Leveling And Trend
On-leveling adjusts historical premium to a common rate level, while trend moves losses, premium, or exposures from an old period to the future period that the selected rate is meant to cover.
- Role
- Concept
- Level
- Core
- Time
- Reference
- Freshness
- Stable
Plain-English Definition
On-leveling and trend solve two different problems. On-leveling removes distortion from past rate changes so the historical premium base can be compared fairly. Trend then pushes losses, premiums, or exposures from the historical period into the future period where the rate will actually apply.
In other words, on-leveling makes old premium comparable to the current rate level, and trend makes old data relevant to the future cost level.
Worked Example
Suppose earned premium from the experience period is 1,000,000, and the average rate level during that period was 12% below the current rate level. The on-level premium is 1,000,000 x 1.12 = 1,120,000.
Now suppose the historical loss cost was 900 per exposure and the appropriate annual loss trend is 6% for two years. The trended loss cost is 900 x (1.06)^2 = 1,011.24.
Those two adjustments are doing different jobs. The first fixes historical premium comparability. The second moves historical cost to the future period your rate needs to fund.
Why Actuaries Use It
Exam 5 includes premium adjustments and trend because a rate indication is only as good as the comparability of its inputs. Old premium at mixed rate levels and old loss costs with no forward trend can easily make a sound method produce a bad answer.
This is also why trend selection is not a clerical afterthought. It is one of the main actuarial judgment points in ratemaking.
Common Mistakes
A common mistake is blending on-leveling and trend together as if they were the same adjustment. They are related, but one corrects for internal rate-level change while the other projects for external time movement.
Another mistake is applying one blanket trend without asking whether severity, frequency, premium, and exposure need different treatment. Exam 5 is not just testing whether you can multiply by a factor. It is testing whether the factor choice makes sense.
Connection To Exam 5
The current outline explicitly calls out premium adjustments such as on-leveling and premium audit, and it separately calls out applying exposure, premium, and loss trends using different approaches.
That makes on-leveling and trend part of the ratemaking spine for Exam 5, not background detail. The loss ratio and pure premium methods depend on them.