A Gravity Model of Mortality Rates for Two Related Populations

Abstract

The mortality rate dynamics between two related but different-sized populations are modeled consistently using a new stochastic mortality model that we call the gravity model. The larger population is modeled independently, and the smaller population is modeled in terms of spreads (or deviations) relative to the evolution of the former, but the spreads in the period and cohort effects between the larger and smaller populations depend on gravity or spread reversion parameters for the two effects. The larger the two gravity parameters, the more strongly the smaller population’s mortality rates move in line with those of the larger population in the long run. This is important where it is believed that the mortality rates between related populations should not diverge over time on grounds of biological reasonableness. The model is illustrated using an extension of the Age-Period-Cohort model and mortality rate data for English and Welsh males representing a large population and the Continuous Mortality Investigation assured male lives representing a smaller related population.     

Policy risk,strategic decisions and contagion effects: Firm‐specific considerations

Research summary : In this article, we investigate the firm‐specific environment and its impact on firm strategy focusing on adverse changes in the policy environment and their effect on divestitures. We argue that experiencing a negative change in the firm‐specific policy environment causes firms to reassess their exposure to policy risk and their ability to manage their policy environment, making them more likely to divest. Operationalizing negative shifts in the firm‐specific policy environment through formal policy disputes between firms and governments, we find that following a dispute, firms are more likely to divest both in the country where the dispute occurs and in other countries in the same region. However, the impact of disputes on divestitures is firm specific, applying only to firms directly involved in a dispute . Managerial summary : What is the impact of change in the firm‐specific environment on firm strategy? We argue that when firms directly experience a negative change in their policy environment that is specific to them, they negatively reassess their exposure to policy risk and their ability to manage their policy environment, which makes them more likely to undertake a divestiture. We analyze formal disputes between firms and governments that arise from adverse changes in policy and find that, following a dispute, firms are more likely to divest in the country where the dispute occurs and in other countries in the same region. However, the impact of disputes on divestitures is firm specific as it applies only to firms directly involved in a dispute . Copyright © 2016 John Wiley & Sons, Ltd.     

A Computationally Efficient Algorithm for Estimating the Distribution of Future Annuity Values Under Interest-Rate and Longevity Risks

Abstract

This paper proposes a computationally efficient algorithm for quantifying the impact of interestrate risk and longevity risk on the distribution of annuity values in the distant future. The algorithm simulates the state variables out to the end of the horizon period and then uses a Taylor series approximation to compute approximate annuity values at the end of that period, thereby avoiding a computationally expensive “simulation-within-simulation” problem. Illustrative results suggest that annuity values are likely to rise considerably but are also quite uncertain. These findings have some unpleasant implications both for defined contribution pension plans and for defined benefit plan sponsors considering using annuities to hedge their exposure to these risks at some point in the future.     

Survivor bias and mutual fund performance

Mutual fund attrition can create problems for a researcher becausefunds that disappear tend to do so due to poor performance.In this article we estimate the size of the bias by trackingall funds that existed at the end of 1976. When a fund mergeswe calculate the return, taking into account the merger terms.This allows a precise estimate of survivorship bias. In addition,we examine characteristics of both mutual funds that mergerand their partner funds. Estimates of survivorship bias overdifferent horizons and using different models to evaluate performanceare provided.     

Respondents' ignoring of attribute information in a choice modelling survey

One debate in economics centres on consumers' decision-making strategies and whether they should be explicitly considered. The default assumption for choice modelling has been that all the attributes presented to respondents somehow influence their choices. More recently, choice modelling research has begun examining how respondents use information. This article presents research that focused on which pieces of information respondents used in responding to a choice modelling survey. The use of information by respondents was captured in the course of the administration of a computer-aided survey, so the research did not rely on posterior self-reporting. Access to the information was captured for each attribute of every alternative, which allowed flexibility in assessing use of information. Three mixed logit models are presented, based on three different assumptions about information use. The results suggest that accounting for respondents' information use affects modelling results, but the impact on estimates of willingness to pay may be relatively small.