Estimation of loss reserves with lognormal development factors

This paper uses a development technique to estimate the loss reserve in a classical run-off triangle setting. Closed-form solutions for unbiased estimates of reserves and their corresponding standard errors can be obtained by assuming lognormal distributions of the development factors. The technique is applied to the Bornhuetter-Ferguson method [Bornhuetter, R.L., Ferguson, R.E., 1972. The actuary and IBNR. Proc. Casualty Actuarial Soc. 59, 181-195] and to two previously studied data sets.