摘要：The United States has experienced a revival of interest in entrepreneurs. While much of the public fascination has focused on "dot com" millionaires and similar high-profile phenomena, a coincident surge in research has focused on the economic foundations of this boom. In executing their research strategy, analysts are confronted with the interrelated issues of deciding "who is an entrepreneur" and identifying data sources suitable to analyze retrepreneurial behavior. In many instances, the focus has been on those individuals who identify themselves as self-employed in large cross-sectional data sets like the Census or Current Population Survey (CPS), or panel data sets such as the Panel Study of Income Dynamics (PSID), Survey of Income and Program Participation (SIPP), National Longitudinal Survey (NLS), or Health and Retirement Study (HRS).
