A wage offer can be either acceptable or unacceptable to a worker, but in cross-sectional and panel data only acceptable wage offers are observed. An OLS wage equation will not reveal how job tenure affects wage offers but rather will reveal how tenure affects acceptable wage offers. By jointly modeling the firm's determination of the wage offer and the worker's decision to accept or reject the offer, we are able to estimate the effect of job tenure on wage offers consistently. In contrast to the usual OLS results, we find that job tenure has no statistically significant effect on wage offers.

Previous work has addressed the relative vulnerability of different auction schemes to collusive bidding. The common wisdom is that ascending-bid and second-price auctions are highly susceptible to collusion. We show that the details of ascending-bid and second-price auctions, including bidder registration procedures and procedures for information revelation during the auction, can be designed to completely inhibit, or unintentionally facilitate, certain types of collusion. If auctions are designed without acknowledging the possibility of collusion then the design will ignore key features that impact the potential success of colluding bidders.

Methods for exact Bayesian inference under a uniform diffuse prior are set forth for the continuous time homogeneous Markov chain model. It is shown how the exact posterior distribution of any function of interest may be computed using Monte Carlo integration. The solution handles the problems of embeddability in a very natural way, and provides (to our knowledge) the only solution that systematically takes this problem into account. The methods are illustrated using several sets of data.

[The axiomatic derivation of mobility indices for first-order Markov chain models in discrete time is extended to continuous-time models. Many of the logical inconsistencies among axioms noted in the literature for the discrete time models do not arise for continuous time models. It is shown how mobility indices in continuous time Markov chains may be estimated from observations at two points in time. Specific attention is given to the case in which the states are fractiles, and an empirical example is presented.]

Models of collusive bidder behavior at single-object second-price and English auctions are provided. The ind ependent private values model is generalized to permit the formulatio n of coalitions and a strategic response by the auctioneer. Cooperati ve strategies are found to be dominant in these models; coalitions of any size are viable, and the payoff to each member increases with th e size of the coalition. In addition, the collusive strategies of the coalition represent a noncooperative equilibrium. The optimal respon se of the auctioneer is to establish a reserve price that is a functi on of the coalition's size. These and other features of the model are found to be consistent with the essential features of actual behavio r.

Allegations of Bidder collusion at Forest Service timber sales in the Pacific Northwest were common in the 1970s. Of course, prices may be low for reasons other than collusion. We formulate an empirical model that allows for both bidder collusion and supply effects and in which we control for demand conditions. Noncooperative behavior in which a single unit is sold (the standard auction model) is a special case: it is found to be definitively outperformed by a model of collusion. We also find that supply effects are dominated by collusion in determining the winning bids in the market.