Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
It has been suggested that an open‐ended follow‐up question should be added to the binary contingent valuation question. Before this is generally recommended, it is important to evaluate the properties of such follow‐up questions. Using a split sample approach, we test whether the open‐ended follow‐up is sensitive to the scope of the commodity being valued. No significant scope effects were detected. It is concluded that the results obtained do not support the use of an open‐ended follow‐up in contingent valuation applications. © 1997 John Wiley & Sons, Ltd.