Dramatic fluctuations in the stock market raise questions about whether actual prices correspond to fundamentals. Even if there are "bubbles", they may not distort real behaviour if managers base investment decisions on fundamentals. Using a new specification testing strategy based on combining...

Empirically, sales are I(1). Starting from this fact, we derive three startling results. First, the variance of production is equal to the variance of sales in the long run. Second, this result holds regardless of the strength of production smoothing, stockout avoidance, or cost shocks. Third,...