Dale Whittington

Administering contingent valuation surveys in developing countries

Abstract Ten years ago only a handful of very rudimentary contingent valuation (CV) studies had been conducted in developing countries; at that time the problems associated with posing hypothetical questions to low-income, perhaps illiterate respondents were assumed to be so overwhelming that one should not even try. Today it is now assumed by many environmental and resource economists and policy analysts working in developing countries that contingent valuation surveys are straightforward and easy to do. This paper examines some of the issues that have arisen and some of the lessons learned over the last 10 years about administering contingent valuation surveys in developing countries. The paper focuses on five issues in particular. 1. (a) explaining to enumerators what a contingent valuation study is all about; 2. (b) interpreting responses to contingent valuation questions; 3. (c) setting referendum prices; 4. (d) constructing joint public-private CV scenarios; 5. (e) ethical problems in conducting such surveys. It is argued that there are numerous issues that arise in contingent valuation work in developing countries that demand careful attention, but that in many respects it is easier to do high-quality contingent valuation surveys in developing countries than in industrialized countries.

Improving the Performance of Contingent Valuation Studies in Developing Countries

This paper discusses three main reasons why so many of the contingentvaluation studies conducted in developing countries are so bad. First,the contingent valuation surveys themselves are often poorly administeredand executed. Second, contingent valuation scenarios are often very poorlycrafted. Third, few CV studies conducted in developing countries aredesigned to test whether some of the key assumptions that the researchermade were the right ones, and whether the results are robust with respectto simple variations in research design and survey method. The paper concludesthat research on stated preference methods in developing countries iscritically important to the successful implementation of these methodsbecause (1) there is no empirical evidence to suggest that rapid,”streamlined” CV surveys yield reliable, accurate results, and (2)there is a significant risk that the current push for cheaper, simplerCV studies could discredit the methodology itself. Moreover, the policydebates to which CV researchers are asked to contribute are often oftremendous importance to the well-being of households in developingcountries. Because the costs of policy mistakes can prove tragic, itis critical that VC researchers push for excellence in this researchenterprise and that funding agencies think more carefully about thevalue of policy-relevant information in the fields in which thecontingent valuation method is being used to study household preferencesand behavior (e.g., water and sanitation services, urban air pollution,soil erosion, deforestation, biodiversity, watershed management,ecosystem valuation, vaccines for the poor).

A study of water vending and willingness to pay for water in Onitsha, Nigeria

Abstract Most people in Onitsha, Nigeria obtain their water from an elaborate and well-organized water vending system which is run by the private sector. About 275 tanker trucks collect water from private boreholes and sell it to households and businesses equipped with water storage facilities. Many of these households and businesses resell water by the bucket to individuals who cannot afford large storage tanks or who cannot be reached by the tanker trucks. During the dry season the private water vending system collects about 24-times as much revenue as the public water utility. On an annual basis, households in Onitsha pay water vendors over twice the operation and maintenance costs of a piped distribution system.

Role of hepatic and intestinal cytochrome P450 3A and 2B6 in the metabolism, disposition, and miotic effects of methadone.

The disposition of the long‐acting opioid methadone, used to prevent opiate withdrawal and treat short‐ and long‐lasting pain, is highly variable. Methadone undergoes N‐demethylation to the primary metabolite 2‐ethyl‐1,5‐dimethyl‐3,3‐diphenylpyrrolinium (EDDP), catalyzed in vitro by intestinal, hepatic, and expressed cytochrome P450 (CYP) 3A4. However, the role of CYP3A4 in human methadone disposition in vivo is unclear. This investigation tested the hypothesis that CYP3A induction (or inhibition) would increase (or decrease) methadone metabolism and clearance in humans.

Role of CYP2B6 in Stereoselective Human Methadone Metabolism

Background:Metabolism and clearance of racemic methadone are stereoselective and highly variable, yet the mechanism remains largely unknown. Initial in vitro studies attributed methadone metabolism to cytochrome P4503A4 (CYP3A4). CYP3A4 was also assumed responsible for methadone clearance in vivo. Nevertheless, recent clinical data do not support a primary role for CYP3A4 and suggest that CYP2B6 may mediate methadone clearance. Expressed CYP2B6 and also CYP2C19 N-demethylate methadone in vitro. This investigation tested the hypothesis that CYPs 2B6, 3A4, and/or 2C19 are responsible for stereoselective methadone metabolism in human liver microsomes and in vivo. Methods:N-demethylation of racemic methadone and individual enantiomers by expressed CYPs 2B6, 2C19, and 3A4 was evaluated. Stereoselective microsomal methadone metabolism was quantified, compared with CYP 2B6 and 3A4 content, and probed using CYP isoform-selective inhibitors. A crossover clinical investigation (control, CYP2B6 and CYP3A4 induction by rifampin, CYP3A inhibition by troleandomycin and grapefruit juice) evaluated stereoselective methadone disposition. Results:At clinical concentrations, methadone enantiomer N-demethylation by recombinant CYPs 2B6, 3A4, and 2C19 was S > R, S = R, and S << R. Greater stereoselective metabolism (S > R) occurred in livers expressing high levels of CYP2B6 compared with CYP3A4. Clopidogrel, troleandomycin, and (+)-N-3-benzyl-nirvanol, selective inhibitors of CYPs 2B6, 3A4, and 2C19, respectively, inhibited microsomal methadone metabolism by 50–60%, 20–30%, and less than 10%. Only inhibition by clopidogrel was stereoselective. Clinically, rifampin diminished both R- and S-methadone plasma concentrations, but troleandomycin and grapefruit juice altered neither R- nor S-methadone concentrations. Plasma R/S-methadone ratios were increased by rifampin but unchanged by CYP3A inhibition. Conclusions:These results suggest a significant role for CYP2B6, but not CYP3A, in stereoselective human methadone metabolism and disposition.

Coping with unreliable public water supplies: Averting expenditures by households in Kathmandu, Nepal

This paper investigates two complementary pieces of data on households’ demand forimproved water services, coping costs and willingness to pay (WTP), from a survey of1500 randomly sampled households in Kathmandu, Nepal. We evaluate how coping costsand WTP vary across types of water users and income. We find that households inKathmandu Valley engage in five main types of coping behaviors: collecting, pumping,treating, storing, and purchasing. These activities impose coping costs on an averagehousehold of as much as 3 U.S. dollars per month or about 1% of current incomes,representing hidden but real costs of poor infrastructure service. We find that thesecoping costs are almost twice as much as the current monthly bills paid to the water utilitybut are significantly lower than estimates of WTP for improved services. We findthat coping costs are statistically correlated with WTP and several householdcharacteristics.

Role of P‐glycoprotein in the intestinal absorption and clinical effects of morphine

There is considerable and unexplained individual variability in the morphine dose‐effect relationship. The efflux pump P‐glycoprotein regulates brain access and intestinal absorption of numerous drugs. Morphine is a P‐glycoprotein substrate in vitro, and P‐glycoprotein affects morphine brain access and pharmacodynamics in animals. However, the role of P‐glycoprotein in human morphine disposition and clinical effects is unknown. This investigation tested the hypothesis that plasma concentrations and clinical effects of oral and intravenous morphine are greater after inhibition of intestinal and brain P‐glycoprotein, with the P‐glycoprotein inhibitor quinidine used as an in vivo probe.

Calculating the value of time spent collecting water: Some estimates for Ukunda, Kenya

Abstract This article presents two procedures for estimating the value of time spent hauling water in developing countries. Both approaches are used to derive estimates of the value of time for households in Ukunda, Kenya. The results indicate that households in this village place a surprisingly high value on the time they spend collecting water, a value approximately equivalent to the wage rate for unskilled labor. These findings suggest that the economic benefits of improved water services in developing countries may be much greater than is commonly realized.

Water and sanitation

Asset management planning provides a structured and auditable process for planning long term investment in infrastructure. The irrigation sector has a pressing need for an efficient means to facilitate strategic investment decisions based upon a clear overview of objectives, options, costs, benefits and competing needs. This paper describes research carried out in Indonesia to assess the feasibility of transferring asset management planning procedures developed for the United Kingdom water industry to the irrigation sector. The 6-month study found notable similarities and some differences between the two applications. Modified procedures were developed accordingly and tested in field trials. It is concluded that there are significant opportunities for the application of the approach as developed in the UK using statistically based sampling procedures. From the experience of the study and the field trials the approach is found to be highly relevant and practicable.

Household demand for improved piped water services: Evidence from Kathmandu, Nepal

Abstract We examine households’ demand for improved water services in Kathmandu, Nepal, where the government is considering the possibility of involving the private sector in the operation of municipal water supply services. We surveyed a randomly selected sample of 1500 households in the Kathmandu Valley and asked respondents questions in in-person interviews about how they would vote if given the choice between their existing water supply situation and an improved water service provided by a private operator. The results provide the first evidence from South Asia that households’ willingness to pay for improved water services is much higher than their current water bills. We find substantial public support among both poor and nonpoor households for a privatization plan that would improve water supply and require all participants to pay regular and higher monthly bills.