  Within the private-values paradigm, we construct a tractable empirical model
of equilibrium behavior at first-price auctions when bidders' valuations are
potentially dependent, but not necessarily affiliated. We develop a test of
affiliation and apply our framework to data from low-price, sealed-bid auctions
held by the Department of Transportation in the State of Michigan to procure
road-resurfacing services: we do not reject the hypothesis of affiliation in
cost signals.
