George Gallup, the pioneer of survey methods and creator of the Gallup poll, created a confidence index in 1938, late in the Great Depression, when he asked Americans, “Do you think business will be better or worse six months from now?” He interpreted the answers as measuring “public optimism” and “the intangible mental attitude which is recognized as one vital element in the week-to-week fluctuations of business activity.”
如今，大多数信心指数都是基于调查问题得出的，受访者被要求评估现今或不久将来的经济局势。1938年大萧条晚期，调查方法先驱、盖洛普调查创始人乔治·盖洛普（George Gallup）创造了一个信心指数。当时他问美国人：“你认为半年后，商业局面会比现在更好还是更差？”他对回答做了分析，用以衡量“公共乐观”和“被视为商业活动周际波动关键影响因素的无形的主观态度”。