Constructing Krinsky and Robb Confidence Interval for Mean and Median WTP Using Stata

The ultimate goal of most non-market valuation studies is to obtain welfare measures i.e. mean and/or median willingness to pay (WTP) and confidence intervals. While the delta (nlcom) and bootstrap (bs) methods can be used for constructing such confidence intervals in Stata, they are not recommended because WTP measures are non-linear functions of random parameters (Creel and Loomis, 1991). The best and widely used approach, which is not available in Stata, consists in simulating the confidence intervals using the Krinsky and Robb procedure (Haab and McConnell, 2002). Hole (2007) has recently introduced a useful command, wtp, which implements the Krinsky and Robb procedure in Stata, but does not feature mean and median WTP estimates and their confidence intervals. I present a Stata command, wtpcikr, which computes mean and median WTP, confidence intervals using the Krinsky and Robb procedure, achieved significance level (ASL) for testing the null hypothesis that WTP equals zero, and a relative efficiency measure (Loomis and Ekstrand, 1998). The command supports both linear and exponential contingent valuation models estimated with or without covariates using the Stata commands probit, logit, biprobit, and xtprobit. I will illustrate the use of wtpcikr by replicating empirical results in Haab and McConnell (2002).

Demand for Electricity Connection in Rural Areas : The Case of Kenya

A modern form of energy, in particular electricity for household use, is an important vehicle in alleviating poverty in developing countries. However, access and costs of connecting to this service for most poor in these countries is inconceivable. Policies promoting electricity connection in rural areas are known to be beneficial in improving the socio-economic and health well-being for households. This paper examines willingness to pay (WTP) for rural electrification connection in Kisumu district, Kenya, using the contingent valuation method (CVM). A nonparametric and a parametric model are employed to estimate WTP values for two electricity products: grid electricity (GE) and photovoltaic (PV) electricity. The results indicate that respondents are willing to pay more for GE services than PV and households favoured monthly connection payments over a lump sum amount. Some of the policies suggested in this paper include: subsidizing the connection costs for both sources of electricity, adjusting the payment periods, and restructuring the market ownership of providing rural electricity services.double bounded; contingent valuation; electricity connection; rural; willingness to pay (wtp)

Poverty rate and government income transfers: A spatial simultaneous equations approach

The poverty rate and income transfer are clearly correlated. However, not much research has attempted to determine the causal linkage between the two. Previous research has primarily focused on the poverty-reducing impact of income transfer. In this paper, we apply a simultaneous equation system of spatial regressions to uncover the spatial pattern of the relationship between the poverty rate and income transfer, using a sample of 3,001 U.S. counties. The results are in line with theoretical expectations; they provide evidence of a significant simultaneity effect between the poverty rate and income transfer. Our findings also confirm the presence of significant spatial autocorrelation. Contrary to previous studies, we find that more generous counties tend to do a better job of reducing poverty and that counties with more poor tend to be less generous, creating incentive for the poor to participate in the labor force. Furthermore, counties located in devolution states perform better in both poverty reduction and income transfer. These findings are missing from extant literature that focuses only on the poverty-reducing impact of welfare payments.endogeneity, income transfer, Poverty, SHAC, spatial econometrics,

Assessing Ohio's Biomass Resources for Energy Potential Using GIS

This recently completed AEDE study funded by Ohio DOD involves a geo-referenced inventory by county of Ohio biomass resources for energy. Categories include forest and crop residues, livestock manure, municipal solid waste and food processing waste. This is an update and expansion of an earlier (1982) inventory of biomass by Hitzhusen et al. It also disaggregates and expands a study by Walsh et al. in 2000 which ranked Ohio 11th among the 50 states in total biomass availability. By estimating and geo-referencing the sustainable quantities of various categories of biomass for energy by county, it is possible to identify the spatial concentrations of various biomass renewable energy feedstocks that may be economically viable for various processes for conversion. These conversion processes in turn have implications for environmental improvement and reduced dependence on foreign oil imports. A better understanding of the technical and economic pros and cons of the most promising conversion processes will be required along with further data collection and refinements of this inventory (particularly the food processing waste subset) before detailed policy recommendations can be made. However, this study is hopefully a good start toward that goal and should provide direction and focus for future analysis and recommendations for a more renewable and sustainable energy and environmental future for Ohio.Availability, Biomass energy, Crop residues, Livestock manure, Wood wastes, Municipal solid wastes.

VLA Imaging of the Disk Surrounding the Nearby Young Star TW Hya

The TW Hya system is perhaps the closest analog to the early solar nebula. We have used the Very Large Array to image TW Hya at wavelengths of 7mm and 3.6 cm with resolutions 0.1 arcseconds (about 5 AU) and 1.0 arcseconds (about 50 AU), respectively. The 7mm emission is extended and appears dominated by a dusty disk of radius larger than 50 AU surrounding the star. The 3.6 cm emission is unresolved and likely arises from an ionized wind or gyrosynchrotron activity. The dust spectrum and spatially resolved 7mm images of the TW Hya disk are fitted by a simple model with temperature and surface density described by radial power laws, $T(r)\propto r^{-0.5}$ and $\Sigma(r) \propto r^{-1}$. These properties are consistent with an irradiated gaseous accretion disk of mass $\sim0.03~{\rm M_{\odot}}$ with an accretion rate $\sim10^{-8}~{\rm M_{\odot}yr^{-1}}$ and viscosity parameter $\alpha = 0.01$. The estimates of mass and mass accretion rates are uncertain as the gas-to-dust ratio in the TW Hya disk may have evolved from the standard interstellar value.Comment: 13 pages, 3 figures, accepted by ApJ Letter

Dealing with Internal Inconsistency in Double-Bounded Dichotomous Choice: An Application to Community-Based Health Insurance

Contingent valuation method is commonly used in the field of health economics in an attempt to help policy maker in taking decisions. The use of the double-bounded dichotomous choice format results in a substantial gain in statistical efficiency over the single bounded dichotomous choice format. Yet, this efficiency gain comes at the cost of biasness known as internal inconsistency. This paper aims at reducing this internal inconsistency in double-bounded dichotomous choice by using the certainty calibration technique in a community-based health insurance study. Findings confirm the internal inconsistency between the initial and the follow-up responses and the statistical efficiency gains of the double-bounded dichotomous choice over the single-bounded dichotomous choice. Furthermore, the use of certainty calibration reduces this internal inconsistent pattern in responses and still maintains efficiency gain. We further discuss the policy implications.Contingent valuation; internal inconsistency; certainty calibration; community-based health insurance

The Spectral Correlation Function -- A New Tool for Analyzing Spectral-Line Maps

The "spectral correlation function" analysis we introduce in this paper is a new tool for analyzing spectral-line data cubes. Our initial tests, carried out on a suite of observed and simulated data cubes, indicate that the spectral correlation function [SCF] is likely to be a more discriminating statistic than other statistical methods normally applied. The SCF is a measure of similarity between neighboring spectra in the data cube. When the SCF is used to compare a data cube consisting of spectral-line observations of the ISM with a data cube derived from MHD simulations of molecular clouds, it can find differences that are not found by other analyses. The initial results presented here suggest that the inclusion of self-gravity in numerical simulations is critical for reproducing the correlation behavior of spectra in star-forming molecular clouds.Comment: 29 pages, including 4 figures (tar file submitted as source) See also: http://cfa-www.harvard.edu/~agoodman/scf/velocity_methods.htm

Short-term contracts: trap or stepping stone toward stable employment?

This paper focuses on labor market transitions and especially on those involving fixed-term contracts. Our contribution is twofold: first, we provide an accurate measure of labor market transitions and focus on transitions from fixed-term contracts to open-ended contracts or unemployment (dealing with the "stepping-stone or dead-end" question) ; second, we analyze the potential incentive effect of fixed-term contracts on effort. To deal with unobserved heterogeneity, we use a dynamic multinomial logit with fixed effects. We estimate the model on the French Labor Force Survey (2002-2008) which provides detailed information on quarterly transitions. We construct an indicator of effort for fixed-term workers based on a compared weekly working time. We find that fixed-term contracts provide slightly better perspectives than unemployment. However, we don't find evidence of any significant impact of working more on the probability of getting an open-ended contract.Fixed-term contracts, effort, transitions