Knowledge that Transforms

This article has been retracted. Please see: https://doi.org/10.1093/restud/rdac085

The growth in labour market participation among women with young children has raised concerns about its implications for child cognitive development. We estimate a model of the cognitive development process of children nested within an otherwise standard model of household behaviour. The household makes labour supply decisions and provides time and money inputs into the child quality production process during the development period. Our empirical results indicate that both parents' time inputs are important for the cognitive development of their children, particularly when the child is young. Money expenditures are less productive in terms of producing child quality. Comparative statics exercises demonstrate that cash transfers to households with children have small impacts on child quality due to the relatively low impact of money investments on child outcomes and the fact that a significant fraction of the transfer is spent on other household consumption and the leisure of the parents.

Entrusting the power to punish to a central authority is a hallmark of civilization, yet informal or horizontal sanctions have attracted more attention of late. We study experimentally a collective action dilemma and test whether subjects choose a formal sanction scheme that costs less than the surplus it makes possible, as predicted by standard economic theory, or instead opt for the use of informal sanctions (IS) or no sanctions. Our subjects choose, and succeed in using, IS surprisingly often, their voting decisions being responsive to the cost of formal sanctions. Adoption by voting enhances the efficiency of both IS and non-deterrent formal sanctions. Results are qualitatively confirmed under several permutations of the experimental design.

This paper asks whether the rapid innovation in Central Processing Units (CPU) results in inefficient elimination of basic Personal Computer (PC) configurations. I estimate a model in which PC makers choose first which CPU options to offer with their products, and then set prices. I contribute to the literature by analyzing a game in which firms make multiple discrete product choices. This requires relaxing point-identifying assumptions, allowing for a large product space, and tackling sample selection problems. I find that the demand for PCs is highly segmented. Using the estimated model in counterfactual analysis, I find that Intel’s introduction of its Pentium M chip contributed significantly to the growth of the mobile segment of the PC market, and to total consumer surplus, while crowding out older technologies. The scope for inefficient product elimination appears to be very limited: the upper bound on the welfare loss appears modest, while the lower bound suggests no welfare loss. I also find that the lion’s share of the short-run effect of innovation is enjoyed by the 20 % least price-sensitive consumers. Important questions regarding complementarities in innovative activities and their associated long-term benefits are left for future research. ∗ I am indebted to my advisors, Steven Berry and Philip Haile, for their continued advice and encouragement. I am also especially grateful to Donald Andrews for his advice. I have benefited greatly from discussions with Eduardo Faingold, Joshua Lustig, fellow graduate students at Yale, and numerous seminar participants. All errors are mine. I am grateful to IDC and to Mr. Steven Clough for making data available. Financial support from the Carl Arvid Anderson Prize Fellowship of the Cowles Foundation is gratefully acknowledged.

Auctions often involve the sale of many related goods: Treasury, spectrum, and electricity auctions are examples. In multi-unit auctions, bids for marginal units may affect payments for inframarginal units, giving rise to “demand reduction” and furthermore to incentives for shading bids differently across units. We establish that such differential bid shading results generically in ex post inefficient allocations in the uniform-price and pay-as-bid auctions. We also show that, in general, the efficiency and revenue rankings of the two formats are ambiguous. However, in settings with symmetric bidders, the pay-as-bid auction often outperforms. In particular, with diminishing marginal utility, symmetric information and linearity, it yields greater expected revenues. We explain the rankings through multi-unit effects, which have no counterparts in auctions with unit demands. We attribute the new incentives separately to multi-unit (but constant) marginal utility and to diminishing marginal utility. We also provide comparisons with the Vickrey auction.

Many structural economics models are semiparametric ones in which the unknown nuisance functions are identified via non-parametric conditional moment restrictions with possibly non-nested or overlapping conditioning sets, and the finite dimensional parameters of interest are over-identified via unconditional moment restrictions involving the nuisance functions. In this article we characterize the semiparametric efficiency bound for this class of models. We show that semiparametric two-step optimally weighted GMM estimators achieve the efficiency bound, where the nuisance functions could be estimated via any consistent non-parametric methods in the first step. Regardless of whether the efficiency bound has a closed form expression or not, we provide easy-to-compute sieve-based optimal weight matrices that lead to asymptotically efficient two-step GMM estimators.

We introduce the concept of a universal social ordering, defined on the set of pairs of an allocation and a preference profile of any finite population. It is meant to unify evaluations and comparisons of welfare (living standards) for individuals and populations of possibly different sizes and preferences. It can be used for policy evaluation, international comparisons, growth assessment, and inequality measurement. It even makes it possible to evaluate policy options that affect the size of the population or the preferences of its members. We study how to extend the theory of social choice in order to select such orderings on a rigorous axiomatic basis. We provide foundations for leximin as well as additively separable criteria. Key ingredients in this analysis are fairness principles in social aggregation, attitudes with respect to population size, and the bases of interpersonal comparisons. We discuss how this sheds light on recent developments in the empirical literature on international comparisons.

This article develops a dynamic asset pricing model with persistent heterogeneous beliefs. The model features competitive traders who receive idiosyncratic signals about an underlying fundamentals process. We adapt Futia's (1981) frequency domain methods to derive conditions on the fundamentals that guarantee non-invertibility of the mapping between observed market data and the underlying shocks to agents' information sets. When these conditions are satisfied, agents remain asymmetrically informed in equilibrium and must ‘forecast the forecasts of others’. An econometrician, who incorrectly imposes a homogeneous beliefs equilibrium, will find that the asset price displays violations of variance bounds, predictability of excess returns, and rejections of cross-equation restrictions.

We show that sellers may earn a reputation for their “ability” to deliver high-quality goods on average by honestly announcing the realized quality of items for sale every period. As the expected revenue stream from continuing with honest communication increases with their ability, high-ability sellers remain honest while low-ability sellers find it too costly and sometimes lie about quality for short-term gain. Thus, cheap-talk communication facilitates the market's learning of a seller's ability and strengthens reputation effects. We study this new reputation mechanism and the induced market dynamics, first when sellers cannot restart with a new identity and second when they can. We extend the analysis to various other situations such as voluntary refund and moral hazard.

We report laboratory experiments that use new, visually oriented software to explore the dynamics of 3×3 games with intransitive best responses. Each moment, each player is matched against the entire population, here 8 human subjects. A “heat map” offers instantaneous feedback on current profit opportunities. In the continuous slow adjustment treatment, we see distinct cycles in the population mix. The cycle amplitude, frequency and direction are consistent with the standard learning models. Cycles are more erratic and higher frequency in the instantaneous adjustment treatment. Control treatments (using simultaneous matching in discrete time) replicate previous results that exhibit weak or no cycles. Average play is approximated fairly well by Nash equilibrium, and an alternative point prediction, “TASP” (Time Average of the Shapley Polygon), captures some regularities that Nash equilibrium misses.