This study used the contingent valuation method (CVM) to measure the benefits of improved air quality in Metro Manila through the adoption of cleaner public transportation. A single-bound dichotomous choice contingent valuation approach using the referendum format was used to estimate the willingness to pay (WTP) from a survey of 1,000 households. The study arrived at WTP estimates for the proposed program ranging from USD3.85 to USD5.77 per month. Income elasticity of WTP was estimated at 0.49. The study also investigated the impact of using secret ballots for eliciting WTP responses to minimize "yea-saying" behavior and reduce social desirability bias.
