The American Customer Satisfaction Index (ACSI) is an economic indicator that measures the satisfaction of consumers across the U.S. economy. It is produced by the National Quality Research Center (NQRC) at the University of Michigan in Ann Arbor, Michigan.

The ACSI interviews about 80,000 Americans annually and asks about their satisfaction with the goods and services they have consumed. Respondents are screened to cover a wide range of business-to-consumer products and services, including durable goods, services, non-durable goods, local government services, Federal government agencies, and so forth. Results from data collection and analysis are released to the public each quarter. ACSI data is used by academic researchers[1], corporations[2][3] and government agencies[4], market analysts and investors[5], industry trade associations, and consumers.

Most importantly, each measured company or organization is given a customer satisfaction index score (an "ACSI score") which reflects a weighted average of three satisfaction proxy questions. Each index score is on a 0-100 scale, and therefore a company can (hypothetically) receive any score ranging from 0 to 100. In practice, scores have tended to range from the low 50's to the high 80's. While slight differences between questionnaires administered to respondents across industries and sectors do exist, the three satisfaction questions used to create the ACSI score for each company are identical. Coupled with the standardized 0-100 index scale, these methods permit comparisons between companies and organizations.

http://en.wikipedia.org/wiki/American_Customer_Satisfaction_Index