When players who choose a common strategy face a common shock, while players who choose different strategies face independent or imperfectly correlated shocks, equilibrium choices exhibit differentiation (respectively emulation) when the sign of the cross-partial derivative of the firms' profit...

We demonstrate that demand uncertainty can explain equilibrium product variety in the presence of sunk costs. Product variety is an efficient response to uncertainty because it reduces the expected costs associated with excess capacity. We find that within the firm's product line, the highest...