How much is the timber from public forests worth? How can the Public Forest Service define a fair market price for standing timber lots? To estimate the value of a timber lot we adopt the transaction-evidence appraisal approach using data from timber auctions in Lorraine (Eastern France) accounting for the facts that: (i) the seller’s reserve prices are secret, (ii) there remain many unsold lots, and (iii) the number of bidders varies from one auction to another. We estimate parameters of a sample selection model in which the hedonic equation includes an endogenous ordinal explanatory variable (the intensity of participation).