You identify a Gazelle by looking at its past growth, not predicting its future prospects. The implication of Birch's research is that no one, including David Birch, knows where new jobs will come from. That is also the conclusion of a trio of more-academic researchers, economists Steven J. Davis of the University of Chicago, John Haltiwanger of the University of Maryland, and Scott Schuh of the Federal Reserve Board. They identify the analytical fallacies that lead people to see job-creation patterns where none exist. And they have done careful empirical research on manufacturing jobs.
Small companies create and destroy jobs at a higher rate , since they start from a smaller base.
Some small firms grow, and some shrink. Some big firms grow, and some shrink. Size alone tells you nothing. None of this is surprising when you think about it. If David Birch or the SBA knew which companies would prosper and add workers, they'd be making a killing in venture capital.