What the claims already incurred will finally cost
Claims are grouped by the year or quarter the loss happened and valued at the end of every later period, from dated payments and dated reserve movements. Anything paid or reserved after the valuation date is left out, so the triangle is rebuilt from history rather than arranged from today's balances, and an old study can be reproduced. Between two development periods an age-to-age factor is worked out three ways — volume-weighted, simple average and the last N origins — and the selected factor is editable, because a study nobody can overrule is a study nobody will sign. The factors chain to an ultimate for each origin, and IBNR is the ultimate less what is already known.







