The NFIB Small Business Optimism Index measures sentiment among United States small and independent owners, not actual output or spending. It comes from the National Federation of Independent Business (a private small business association) via its research arm and monthly Small Business Economic Trends survey. It began quarterly in the fourth quarter of 1973 and monthly in 1986, using random draws from NFIB membership files by mail plus 1 reminder.
Usable replies run from a few hundred to about 1700, with no state or regional split and no coverage of large firms or consumers. A companion Uncertainty Index sums "Don't Know" and "Uncertain" answers across 6 questions against an average of 68.