Cameron, T. A. (1992) “Nonuser Resource Values,” American Journal of Agricultural Economics, 74 (5), 1133-37.
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Kling, C. L. (1997) “The gains from combining travel cost and contingent valuation data to value nonmarket goods,” Land Economics, 73 (3), 428-439.
This paper provides a critical assessment of the improvements in precision and bias to welfare measures from combining contingent valuation and travel cost data. Simulation experiments are performed using a variation of the model first suggested by Cameron (1992a) with a focus an identifying likely lower bounds on these gains. fn addition to examining single- bounded contingent valuation as a component of the combined model, this paper investigates additional gains that may accrue from employing a double-bounded variant of contingent valuation. Sizable gains in both bias and precision are found in the simulation experiments. The results suggest that additional investigation into these models is warranted.
Choe, K. A., D. Whittington, and D. T. Lauria (1996) “The economic benefits of surface water quality improvements in developing countries: A case study of Davao, Philippines,” Land Economics, 72 (4), 519-537.
Two nonmarket valuation techniques-the contingent valuation method and travel cost model-are used to estimate the economic value that people in Davao, Philippines, place on improving the water quality of the rivers and sea near their community. The contingent valuation and travel cost estimates are very close to each other and are quite low both in absolute terms and as a percentage of household income. These findings suggest that water pollution control is simply not a high priority for Davao's residents, and support the argument that households' willingness to pay for environmental amenities such as improved water quality is low.
Whitehead, J. C. (1995) “Willingness-to-Pay For Quality Improvements - Comparative Statics and Interpretation of Contingent Valuation Results,” Land Economics, 71 (2), 207-215.
This paper extends variation function theory by examining the effects of changes in prices, quality, and income on willingness to pay for quality change. Comparative static effects are found for both on-site users and nonusers of the resource. These results are used to interpret contingent valuation empirical models. For example, the substitution and complementary relationships between trips to natural resource sites can be identified. This paper also suggests tests for comparison of contingent valuation with recreation demand models and other tests of validity.
Mazzotta, M. J., and J. Kline (1995) “Environmental Philosophy and the Concept of Nonuse Value,” Land Economics, 71 (2), 244-249.
Randall, A. (1994) “A Difficulty With the Travel Cost Method,” Land Economics, 70 (1), 88-96.
Instead of observable prices of recreational visits, travel cost method (TCM) researchers are obliged to substitute researcher-assigned visitation cost estimates. I argue that visitation costs are inherently subjective, but are ordinally measurable so long as the cost increases with distance travelled. It follows that traditional TCM yields only ordinally measurable welfare estimates. The household production function formulation of TCM ''resolves'' this problem only by imposing severe and untestable analytical restrictions. TCM cannot serve as a stand-alone technique for estimating recreation benefits; rather, it must be calibrated using information generated with fundamentally different methods.