Economic experts play a key role in showing common impact at class certification. Unfortunately, the primary tool in the economist’s toolkit—regression analysis—produces an average price (or wage) effect, which by itself cannot demonstrate that all or almost all members of a class have suffered antitrust injury. To connect an average price (or wage) effect to all class members, an economist can develop evidence of a pricing structure; evidence that all prices (or wages) move together according to common factors (or due to considerations of internal equity) implies that an average effect likely reflects the movement of all or almost all prices (or wages). Alternatively, an economic expert can deploy more advanced regression methods, which permit the effect of the conduct variable to vary by buyer (or worker); this method is viable, however, under certain conditions. Finally, the primary regression used to establish average price (or wage) effects can be used to predict prices (or wages) by buyer (or worker), based on the buyer’s (worker’s) unique characteristics.