Risk Aversion and Planning Horizons
放弃偏好可加分离假设，发现当不同时期消费为特定替代品时，风险厌恶随规划期长度增加而增加，这解释了老年人增加风险资产持有比例的经验发现。
A number of empirical studies seem to reject the additive separability of preferences that is assumed in most theoretical models of the life cycle. We show that, when additive separability is abandoned and interactions between consumptions at different dates are taken into account, an interesting relation emerges between risk aversion and length of the planning horizon. Specifically, we show that when consumptions at different dates are specific substitutes, risk aversion increases with horizon length. This may explain the surprising empirical finding that individuals seem to increase the share of wealth held in risky assets as they become older.