The Aggregation of Climate Change Damages: a Welfare Theoretic Approach

The economic value of environmental goods is commonly determined using the concepts of willingness to pay (WTP) or willingness to accept (WTA). However, the WTP/WTA observed in different countries (or between individuals) will differ according to socio-economic characteristics, in particular income. This notion of differentiated values for otherwise identical goods (say, a given reduction in mortality risk) has been criticized as unethical, most recently in the context of the 'social cost' chapter of the IPCC Second Assessment Report. These critics argue that, being a function of income, WTP/WTA estimates reflect the unfairness in the current income distribution, and for equity reasons uniform per-unit values should therefore be applied across individuals and countries. This paper analyses the role of equity in the aggregation of climate change damage estimates, using basic tools of welfare economics. It shows one way of how WTP/WTA estimates can be corrected in aggregation if the underlying income distribution is considered unfair. It proposes that in the aggregation process individual estimates be weighted with an equity factor derived from the social welfare and utility functions. Equity weighting can significantly increase aggregate (global) damage figures, although some specifications of weighting functions also imply reduced estimates. The paper also shows that while the postulate of uniform per-unit values is compatible with a wide range of 'reasonable' utility and welfare specifications, there are also cases where the common-value notion is not compatible with defensible welfare concepts.     

Visibility Bias in the Transmission of Consumption Beliefs and Undersaving

We model visibility bias in the social transmission of consumption behavior. When consumption is more salient than nonconsumption, people perceive that others are consuming heavily, and infer that future prospects are favorable. This increases aggregate consumption in a positive feedback loop. A distinctive implication is that disclosure policy interventions can ameliorate undersaving. In contrast with wealth-signaling models, information asymmetry about wealth reduces overconsumption. The model predicts that saving is influenced by social connectedness, observation biases, and demographic structure, and provides new insight into savings rates. These predictions are distinct from other common models of consumption distortions.     

Treasury Safety,Liquidity, and Money Premium Dynamics: Evidence from Debt Limit Impasses

Treasury securities enjoy a “money premium” because they are ultra-safe and liquid. However, during debt limit impasses, the safety and liquidity of Treasury securities temporarily deteriorate, eroding the money premium. Using past impasses, we find the money premium eroded by roughly six basis points across all Treasury securities and up to 50 basis points for the shortest maturities at the greatest risk of a delayed principal payment. Safety and liquidity each accounted for about half of the erosion. The deterioration of safety and liquidity also appears to interact, consistent with theories of default-driven liquidity risk and the information sensitivity of debt.     

Naïve Buying Diversification and Narrow Framing by Individual Investors

We provide the first tests to distinguish whether individual investors equally balance their overall portfolios (naïve portfolio diversification, NPD) or, in contrast, equally balance the values of same-day purchases of multiple assets (naïve buying diversification, NBD). We find NBD in purchases of multiple stocks, and in mixed purchases of individual stocks and funds. In contrast, there is little evidence of NPD. Evidence suggests that NBD arises due to stock picking behavior and neglect of diversification. These findings suggest that behavioral finance theory should incorporate transaction, as well as portfolio, framing.