Prices, Unit Values and Local Measurement Units in Rural Surveys: an Econometric Approach with an Application to Poverty Measurement in Ethiopia

For many research problems in developing countries, some information on prices faced by households is required, for example if subsistence consumption is a substantial part of consumption. These prices are not readily available from household surveys, and at times they are not easily observed, for example if markets are thin and systematic price information can only be observed from markets some distance away from communities. Furthermore, quantities consumed and produced are often in local units presenting further problems for the analysis. We provide an econometric approach to estimate prices and quantity conversion factors from household expenditure data, using data from rural Ethiopia to illustrate the approach. In an application, we show that the conclusions about poverty changes over time are significantly affected by using alternative strategies to convert local units and to value subsistence consumption. We find in our case that mean unit values result in the overestimation of prices due to outliers and other sources of measurement error. Exogenous consumer price sources, often collected at larger markets outside the village, tend to give slightly lower values than our estimates.household surveys, unit values, subsistence consumption, local measurement units, poverty

Prices, unit values and local measurement units in rural surveys: an econometric approach with an application to poverty measurement in Ethiopia

For many research problems in developing countries, some information on prices faced by households is required for the analysis, for example if subsistence consumption is a substantial part of consumption. These prices are not readily available from household surveys, nor is it straightforward to observe them. Furthermore, quantities consumed and produced are often in local units presenting further problems for the analysis. We provide an econometric approach to estimate prices and quantity conversion factors from household expenditure data. We use panel data from rural Ethiopia to illustrate the approach and to investigate the potential exogenous quality bias in the estimation of the prices. In an application, we show that the conclusions about poverty changes over time are significantly affected by using less appropriate strategies to convert local units and to value subsistence consumption. We find that mean unit values result in the overestimation of prices due to outliers and other sources of measurement error. Exogenous consumer price sources, often collected at larger markets outside the village, tend to be slightly lower than our estimates.household surveys, unit values, subsistence consumption, local measurement units, poverty

Speeding up Permutation Testing in Neuroimaging

Multiple hypothesis testing is a significant problem in nearly all neuroimaging studies. In order to correct for this phenomena, we require a reliable estimate of the Family-Wise Error Rate (FWER). The well known Bonferroni correction method, while simple to implement, is quite conservative, and can substantially under-power a study because it ignores dependencies between test statistics. Permutation testing, on the other hand, is an exact, non-parametric method of estimating the FWER for a given $\alpha$-threshold, but for acceptably low thresholds the computational burden can be prohibitive. In this paper, we show that permutation testing in fact amounts to populating the columns of a very large matrix ${\bf P}$. By analyzing the spectrum of this matrix, under certain conditions, we see that ${\bf P}$ has a low-rank plus a low-variance residual decomposition which makes it suitable for highly sub--sampled --- on the order of $0.5\%$ --- matrix completion methods. Based on this observation, we propose a novel permutation testing methodology which offers a large speedup, without sacrificing the fidelity of the estimated FWER. Our evaluations on four different neuroimaging datasets show that a computational speedup factor of roughly $50\times$ can be achieved while recovering the FWER distribution up to very high accuracy. Further, we show that the estimated $\alpha$-threshold is also recovered faithfully, and is stable.Comment: NIPS 1

Exchange Rate Dynamics and Fundamental Equilibrium Exchange Rates

The paper investigates if the most popular alternative to the purchasing parity power approach (PPP) to estimate equilibrium exchange rates, the fundamental equilibrium exchange rate (FEER) influences exchange rate dynamics in the long run. For a large panel of industrialized and emerging countries and on the period 1982-2007, we detect the presence of unit roots in the series of real effective exchange rates and in the series of FEERs. We find and estimate a cointegration relationship between real effective exchange rates and FEERs. The results show that the FEER has a positive and significant influence on exchange rate dynamics in the long run.Fundamental equilibrium exchange rates; Panel unit root tests; Global imbalances; Fully modified ordinary least square; Dynamic ordinary least square; Pooled Mean Group

Health Expenditure and Income in the United States

This paper investigates the long-run economic relationship between health care expenditure and income in the US at a State level. Using a panel of 49 US States followed over the period 1980-2004, we study the non-stationarity and cointegration between health spending and income, ultimately measuring income elasticity of health care. The tests we adopt allow us to explicitly control for cross-section dependence and unobserved heterogeneity. Specifically, in our regression equations we assume that the error is the sum of a multifactor structure and a spatial autoregressive process, which capture global shocks and local spill overs in health expenditure. Our results suggest that health care is a necessity rather than a luxury, with an elasticity much smaller than that estimated in other US studies. Further, we observe a significant spatial spill over, though with a smaller intensity than that detected in other studies on spatial concentration of US health spending. Our broad perspective of cross section dependence as well as the methods used to capture it give new insights on the debate over the relationship between health spending and income.Health expenditure; income elasticity; cross section dependence; panels

The Mexican Wage Curve 2000-2003: A Quantile Analysis

This paper exploits the Mexican Encuesta Nacional de Empleo Urbano (ENEU) to determine the existence of the wage curve—an empirical phenomena first suggested by Blanchflower and Oswald (1990)—during the period 2000–2003. We propose an innovative approach to the wage curve by estimating the elasticity across the wage distribution. This is applied to the Mexican experience during the early 2000s recession. The evidence indicates that for Mexico during this period there is no wage curve, and that wages are positively affected by local levels of unemployment. This lends credibility to the Harris and Todaro (1970) view which suggests that there is segmentation in the labour market with residual unemployment. We argue that perhaps the power of unions may account for our findings

Unit roots and cointegration in panels

This paper provides a review of the literature on unit roots and cointegration in panels where the time dimension (T), and the cross section dimension (N) are relatively large. It distinguishes between the first generation tests developed on the assumption of the cross section independence, and the second generation tests that allow, in a variety of forms and degrees, the dependence that might prevail across the different units in the panel. In the analysis of cointegration the hypothesis testing and estimation problems are further complicated by the possibility of cross section cointegration which could arise if the unit roots in the different cross section units are due to common random walk components. --Panel Unit Roots,Panel Cointegration,Cross Section Dependence,Common Effects