FA-63585 / Actuarial life tables / Member archive

Mortality improvement projection: Projected rates can exceed one · case 05

De-improved old-age rates exceed one.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Input q {age: per 100000 at base_year}, aa {age: annual improvement per 10000}, age, year, n, mode static|generational. For k<n: attained age age+k, projection year = year+k (generational) or year (static); q = min(1, q_base*(1-AA)^(year-base)) with negative exponents de-improving. Missing age -> 'missing age <a>'. Return rates rounded to 8.

Why this case matters

Life-table arithmetic compounds across ages, so one misplaced index or assumption shifts every downstream value.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
de-improvement near one	`[0.01986829, 1.16252353]`	`[0.01986829, 1.0]`	Failed

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