Bateman, I. J., & Langford, I. H. (January 01, 1997). Budget-constraint, temporal, and question-ordering effects in contingent valuation studies. Environment & Planning A, 29, 7, 1215.

In this article the authors create two contingent valuation studies, each with minor variation to do determine the effects of budget-contraints, ordering of questions, and timeline proposed in the survey.Their literature review reveals that many other researchers were discontented with the lack of consideration for budget restraints in past contingent valuations. The study found that including a question regarding the respondents budget constraints resulted in a substantial increase in their stated value for the good in question.