Immediate Annuity Pricing in the Presence of Unobserved Heterogeneity
North American Actuarial Journal
One of the acknowledged difficulties with pricing immediate annuities is that underwriting the annuitant's life is the exception rather than the rule. In the absence of underwriting, the price paid for a life-contingent annuity is the same for all sales at a given age. This exposes the market (insurance company and potential policyholder alike) to antiselection. The insurance company worries that only the healthiest people choose a life-contingent annuity and therefore adjust mortality
... mortality accordingly. The potential policyholders worry that they are not being compensated for their relatively poor health and choose not to purchase what would otherwise be a very beneficial product. This paper develops a model of underlying, unobserved health. Health is a state variable that follows a first-order Markov process. An individual reaches the state "death" either by accident from any health state or by progressively declining health state. Health state is one-dimensional, in the sense that health can either "improve" or "deteriorate" by moving further or closer to the "death" state, respectively. The probability of death in a given year is a function of health state, not of age. Therefore, in this model a person is exactly as old as he feels. We first demonstrate that a multistate, ageless Markov model can match the mortality patterns in the common annuity mortality tables. The model is extended to consider several types of mortality improvements: permanent through decreasing probability of deteriorating health; temporary through improved distribution of initial health state; and plateau through the effects of past health improvements. We then construct an economic model of optimal policyholder behavior, assuming that the policyholder either knows his health state or has some limited information. The value of mortality risk transfer through purchasing a life-contingent annuity is estimated for each health state under various risk-aversion parameters. Given the economic model for optimal purchasing of annuities, the value of underwriting (limited information about policyholder health state) is demonstrated.