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Andreoni and Sprenger (2012a, b) report evidence that distinct utility functions govern choices under certainty and risk. I investigate the robustness of this result to the experimental design. I find that the effect disappears completely when a multiple price list instrument is used instead of a convex time budget design. Alternatively, the effect is reduced by half when sooner and later payment risks are realized using a single lottery instead of two independent lotteries. The result is thus at least partially driven by intertemporal diversification, supporting an explanation in terms of concavity of the intertemporal, and not only atemporal, utility function. (JEL C91, D81, D91)The past decade has seen rapid advances in the development of both experimental designs and estimation procedures to measure the utility and discount functions that govern individual choices over time. These advances are significant both because many important economic decisions entail consequences at different points in time, and because a substantial earlier literature found wide disparities in estimated discount rates-including many that seem extraordinarily large. 1 One important reason for these high discount rate estimates is the fact that estimates which assume a linear utility function will be upwardly biased when the utility function is, in fact, concave. This is because under concave utility, both diminishing marginal utility and discounting for time delay will tend to favor the choice of a smaller, sooner reward. Therefore, if the former is assumed away, then the effect of the latter will be overstated. The recent literature identifies at least three approaches to correcting for this bias. These are the joint estimation strategy 1 This early literature is thoroughly reviewed by Frederick, Loewenstein, and O'Donoghue (2002).

A major challenge in conducting classroom experiments for larger classes is the complexity of assembling responses and reporting feedback to students. The author demonstrates how mobile phone text messaging can be used to overcome the limitations of pencil-and-paper experiments without incurring the costs of full computerization. Students submit responses as text messages, which are downloaded into a spreadsheet for automated analysis and by return messaging. The author presents examples of experiments that have been conducted successfully using text messaging as the response medium. These can be run in any room from which the instructor can access the internet and are designed to economize on both class time and effort of the instructor.

Many households have insufficient savings to handle moderate and routine consumption shocks. Many of these financially-fragile households also have the highest lottery expenditures as a proportion of income. This combination suggests that Prize-Linked Savings (PLS) accounts, combining security of principal with lottery-type jackpots, can increase savings among these at-risk households. Results from an online experiment show that the introduction of PLS accounts increase total savings and reduce lottery expenditures significantly, especially among individuals with the lowest levels of savings and income. The results imply that PLS accounts offer a plausible market-based solution to encourage individuals to increase savings. JEL Codes: D14, G11, E21, C91, L83, D12.