About Me:

I am a behavioral economist, with interests in public finance and health economics. I earned a Ph.D. in economics from UC Berkeley, and am currently completing a Robert Wood Johnson Foundation fellowship at Harvard. I will be joining the department of Economics at the London School of Economics in Fall 2011.

We develop a model that parsimoniously captures habit-formation, projection bias, and present bias in an intertemporal choice setting, and conduct a field experiment to calibrate the parameters of the model. Building on the gym-attendance study of Charness and Gneezy (2009), we incentivize subjects to attend the gym for a month, observe their pre- and post-treatment attendance relative to a control group, and elicit their pre- and post-treatment predictions of post-treatment attendance. We find that subjects form a short-run habit similar to that found by Charness and Gneezy, although there is now evidence of substantial decay caused by the shock of the semester break. Moreover, subjects appear not to embed habit formation into their ex-ante predictions. We additionally find that subjects greatly over-predict future attendance, which we interpret as evidence of partial naivete with respect to present bias. We estimate a structural model to identify the key parameters and interpret the economic significance of the habit. We find that approximately one-third of subjects formed a habit equivalent to a $2.60 per-visit subsidy, while their predictions are consistent with 90% projection bias over the habit formation. Subjects are also substantially naive about their self-control problems: the structural results indicate they expect their future selves to be two-thirds less "present biased" than they currently are. This experiment provides novel estimates of important economic parameters, and explains a pattern of procrastination and underinvestment in health.
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I empirically test smoking data for two biases from the behavioral economics literature. I use MSA-level variation in cigarette price shocks over a 26-year span to examine individual smoking responses to current and predicted future prices, and to price volatility. I use mature smokers' responses to estimate a short-run discount factor β in the range [0.71,0.89] and long-run discount factor δ approximately 0.9. With an additional assumption on the utility function, I use the under-response to price volatility to estimate a degree of projection bias α in the range [0.41,0.49], meaning that people underestimate changes in tastes from smoking behavior by 40%. Overall, I find that a combination of present bias and projection bias explains significant, and potentially costly, deviations from rational cigarette consumption.
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I use subjects' valuations of a contingent-payment security to obtain incentive-compatible predictions of their own willingness to perform an affectively neutral, but time-consuming, future task. By comparing predicted behavior with actual subsequent actions, I can calibrate a model of partially naive present-biased preferences. Results are also obtained for inter-personal predictions, allowing me to investigate overconfidence and inter-personal projection.

I conduct a field experiment designed to measure state-contingent prediction errors made by current smokers about their willingness to refrain from smoking in the future. Systematic biases about the disutility of abstention will cause smokers to make inefficient choices about quitting: they may make too many attempts (if they are in a relatively low craving state at the outset of a quit attempt) or too few (if they tend to project maximal withdrawal).

This project formalizes and calibrates a model of 'exponential growth bias' -- a systematic error in subjective assessments of exponential growth -- and examines its role in a range of household finance settings. We intend to move from a laboratory setting (where we investigate the key characteristics of the bias) to a market setting (where we investigate its external validity, and the use of 'de-biasing' tools.

I test for two sources of bias in predictions of future driving by exploiting geographic variation in used vehicle sale prices---as measured by the Edmunds.com "True Market Value" and regional predictions published in the Energy Information Administration's "Short-Term Energy Outloook". I find a short-run discount factor beta that is not significantly different from one, but imprecisely estimated. Comparing the response implied by this previous research to the response estimated in the data, I find evidence that consumers somewhat over-respond to changes in the current fuel price. Although only marginally significant, this suggests that consumers may be focusing too much on the current fuel price and too little on predictable changes in the future.

Teaching:

While my current RWJ fellowship is a research-only position, I have previously taught discussion sections for undergraduate economics classes at UC Berkeley:

• Econ 100a, Intermediate Microeconomics, Summer 2005 and Summer 2007


• Econ C110, Game Theory, Fall 2006


• Econ 119a, Psychology and Economics, Spring 2007

I received an Outstanding Graduate Student Instructor award for the 2007-2008 school year. Teaching evaluations and summaries are available upon request.

Former students looking for .pdf lecture notes and slides may contact me directly.