The Stylized Facts of Entry. I was just reading Paul Geroski's "What do we know about entry?" International Journal of Industrial Organization, 1995. It's a well-written survey of empirical patterns like the following:

Stylized fact 2. Although there is a very large cross-section variation in entry, differences in entry between industries do not persist for very long. In fact, most of the total variation in entry across industries and over time is 'within' industry variation rather than 'between' industry variation. Stylized fact 3. Entry and exit rates are highly positively correlated, and net entry rates and penetration are modest fractions of gross entry rates and penetration.