Christopher Udry

Bio: Christopher Udry is an academic researcher from Northwestern University. The author has contributed to research in topics: Consumption (economics) & Financial market. The author has an hindex of 44, co-authored 103 publications receiving 14287 citations. Previous affiliations of Christopher Udry include Yale University & Center for Economic and Policy Research.

Learning About a New Technology: Pineapple in Ghana

Abstract: This paper investigates the role of social learning in the diffusion of a new agri cultural technology in Ghana. We use unique data on farmers' communication patterns to define each individual's information neighborhood. Conditional on many potentially confounding variables, we find evidence that farmers adjust their inputs to align with those of their information neighbors who were surpris ingly successful in previous periods. The relationship of these input adjustments to experience further indicates the presence of social learning. In addition, applying the same method to input choices for another crop, of known technol ogy, correctly indicates an absence of social learning effects. (JEL D83, 013, 033, Q16)

Gender, Agricultural Production, and the Theory of the Household

Abstract: Virtually all models of the household assume that the allocation of resources is Pareto efficient. Within many African households, agricultural production occurs on many plots controlled by different members of the household. Pareto efficiency implies that factors should be allocated efficiently across these plots. I find, in contrast, that plots controlled by women are farmed much less intensively than similar plots within the household controlled by men. The estimates imply that about 6 percent of output is lost because of inefficient factor allocation within the household. The paper suggests a new approach to modeling intrahousehold allocation consistent with the empirical results.

Risk and Insurance in a Rural Credit Market: An Empirical Investigation in Northern Nigeria

Abstract: Credit contracts play a direct role in pooling risk between households in northern Nigeria. Repayments owed by borrowers depend on realizations of random shocks by both borrowers and lenders. The paper develops two models of state-contingent loans. The first is a competitive equilibrium in perfectly enforceable contracts. The second permits imperfect information and equilibrium default. Estimates of both models indicate that quantitatively important state-contingent payments are embedded in these loan transactions, but that a fully efficient risk-pooling equilibrium is not achieved. The research is based on a year-long survey in Zaria, Nigeria conducted by the author.

The Profits of Power: Land Rights and Agricultural Investment in Ghana

Abstract: We examine the impact of ambiguous and contested land rights on investment and productivity in agriculture in Akwapim, Ghana. We show that individuals who hold powerful positions in a local political hierarchy have more secure tenure rights and that as a consequence they invest more in land fertility and have substantially higher output. The intensity of investments on different plots cultivated by a given individual corresponds to that individual’s security of tenure over those specific plots and, in turn, to the individual’s position in the political hierarchy relevant to those specific plots.

Drought and Saving in West Africa: Are Livestock a Buffer Stock?

Abstract: Households in the west African semi-arid tropics face substantial risk -- an inevitable consequence of engaging in rainfed agriculture in a drought-prone environment. It has long been hypothesized that these households keep livestock as a buffer stock to insulate their consumption from income fluctuations income. This paper tests this hypothesis. Results indicate that livestock transactions play less of a consumption smoothing role than often assumed. Livestock sales compensate for at most thirty percent, and probably closer to twenty percent of income shortfalls due to village-level shocks alone. We discuss possible explanations for these results and suggest directions for future work.

Econometric Analysis of Cross Section and Panel Data

Abstract: The second edition of this acclaimed graduate text provides a unified treatment of two methods used in contemporary econometric research, cross section and data panel methods. By focusing on assumptions that can be given behavioral content, the book maintains an appropriate level of rigor while emphasizing intuitive thinking. The analysis covers both linear and nonlinear models, including models with dynamics and/or individual heterogeneity. In addition to general estimation frameworks (particular methods of moments and maximum likelihood), specific linear and nonlinear methods are covered in detail, including probit and logit models and their multivariate, Tobit models, models for count data, censored and missing data schemes, causal (or treatment) effects, and duration analysis. Econometric Analysis of Cross Section and Panel Data was the first graduate econometrics text to focus on microeconomic data structures, allowing assumptions to be separated into population and sampling assumptions. This second edition has been substantially updated and revised. Improvements include a broader class of models for missing data problems; more detailed treatment of cluster problems, an important topic for empirical researchers; expanded discussion of "generalized instrumental variables" (GIV) estimation; new coverage (based on the author's own recent research) of inverse probability weighting; a more complete framework for estimating treatment effects with panel data, and a firmly established link between econometric approaches to nonlinear panel data and the "generalized estimating equation" literature popular in statistics and other fields. New attention is given to explaining when particular econometric methods can be applied; the goal is not only to tell readers what does work, but why certain "obvious" procedures do not. The numerous included exercises, both theoretical and computer-based, allow the reader to extend methods covered in the text and discover new insights.

Evolution and Rationality Some Recent Game-Theoretic Results. Identification and Estimation of Local Average Treatment Effects

Abstract: We investigate conditions sufficient for identification of average treatment effects using instrumental variables. First we show that the existence of valid instruments is not sufficient to identify any meaningful average treatment effect. We then establish that the combination of an instrument and a condition on the relation between the instrument and the participation status is sufficient for identification of a local average treatment effect for those who can be induced to change their participation status by changing the value of the instrument. Finally we derive the probability limit of the standard IV estimator under these conditions. It is seen to be a weighted average of local average treatment effects.

Selection on Observed and Unobserved Variables: Assessing the Effectiveness of Catholic Schools

Abstract: We develop estimation methods that use the amount of selection on the observables in a model as a guide to the amount of selection on the unobservables. We show that if the observed variables are a random subset of a large number of factors that influence the endogenous variable and the outcome of interest, then the relationship between the index of observables that determines the endogenous variable and the index that determines the outcome will be the same as the relationship between the indices of unobservables that determine the two variables. In some circumstances this fact may be used to identify the effect of the endogenous variable. We also propose an informal way to assess selectivity bias based on measuring the ratio of selection on unobservables to selection on observables that would be required if one is to attribute the entire effect of the endogenous variable to selection bias. We use our methods to estimate the effect of attending a Catholic high school on a variety of outcomes. Our main conclusion is that Catholic high schools substantially increase the probability of graduating from high school and, more tentatively, college attendance. We do not find much evidence for an effect on test scores.

Selection on Observed and Unobserved Variables: Assessing the Effectiveness of Catholic Schools

Abstract: In this paper we measure the effect of Catholic high school attendance on educational attainment and test scores. Because we do not have a good instrumental variable for Catholic school attendance, we develop new estimation methods based on the idea that the amount of selection on the observed explanatory variables in a model provides a guide to the amount of selection on the unobservables. We also propose an informal way to assess selectivity bias based on measuring the ratio of selection on unobservables to selection on observables that would be required if one is to attribute the entire effect of Catholic school attendance to selection bias. We use our methods to estimate the effect of attending a Catholic high school on a variety of outcomes. Our main conclusion is that Catholic high schools substantially increase the probability of graduating from high school and, more tentatively, attending college. We find little evidence of an effect on test scores.