预期寿命、年金市场与经济行为

Life Expectancy, Annuity Markets and Economic Behaviors

随着经济的发展,人口预期寿命持续增加,社会养老压力逐步加大;年金作为养老保障的重要支柱,其需求也在不断增大。文章在一个包含信贷约束和年金市场的三期生命周期模型框架下,从理论上分析了预期寿命增加和年金市场发展对典型消费者人力资本投资、储蓄行为、退休决策和预期终生劳动供给的影响。研究发现,随着预期寿命的增加,消费者会增加人力资本投资水平,增加储蓄率,但是退休行为和预期终生劳动供给的变化不确定,取决于年金市场的完善程度和外生的市场利率水平。如果年金市场不完善程度较高或市场利率水平较低,预期寿命增加会引起退休提前。但是即使进入劳动力市场的时间推迟,退出劳动力市场的时间提前,由于生存概率增加,预期终生劳动供给的变化并不确定。文章还发现,当预期寿命保持不变时,随着年金市场的不断完善,消费者会提前退休。

In the past century,life expectancy in most countries has increased. At the same time,there is an increasing demand for the development of annuity markets. In this paper,we construct a three-period lifecycle model with credit constraints and annuity markets,and investigate the effects of increasing life expectancy and the development of annuity markets on individuals’ optimal choices of the length of schooling,saving behavior,retirement length and expected lifetime total labor supply. Within this framework,we find that as life expectancy increases,individuals choose to gain more education and increase savings,but how they are going to change the retirement decision and expected lifetime labor supply depends on the maturity of annuity markets and the interest rate in the economy. If there is no mature annuity market,or if the interest rate is low,as life expectancy increases,individuals will retire earlier.However,since the survival rate also increases,expected lifetime labor supply may not decline even when labor supply at the two end stages of life does. We also find that if life expectancy remains unchanged,as annuity markets develop,individuals will retire earlier. The robustness of the results has been checked with numerical examples. Our work is part of an important literature that tries to explain the'Ben-Porath puzzle'raised by Hazan(2009),who shows that a necessary condition for the Ben-Porath mechanism(Ben-Porath,1967)to hold is that increased life expectancy must also increase expected lifetime labor supply,which is not supported by empirical evidence. The main contributions of our paper are as follows:First,we introduce the annuity market,which is closely linked with life expectancy and retirement,to the model when revisiting the BenPorath mechanism. We emphasize the importance of annuity markets when analyzing the effects of increasing life expectancy on individuals’ behaviors,and also show that the development of annuity markets will have an effect on individuals’ optimal choice. Second,we not only analyze the effects of increasing life expectancy and the development of annuity markets on individuals’ retirement decision,but also focus on the effects on individuals’ expected lifetime labor supply,which is affected by both mortality rates and labor supply in each period. This makes our results comparable to the empirical findings by Hazan(2009).