How do we know that customers are less satisfied than in the past? One widely used measure is the American Customer Satisfaction Index. A national economic indicator of product and service evaluations, the index has been updated quarterly for the past decade.

New sectors replace old ones as needed, and the survey represents scores from about 200 companies in 39 industries. The ACSI is produced by the University of Michigan Business School, the American Society for Quality, and CFI Group.

The historic data on the chart shows that even as overall product quality improved, the index—based on a 100-point scale—declined each year from 1994 to 1997. It has remained below 1994 levels ever since.

In particular, the most recent data for fourth quarter 2004 shows that E-commerce satisfaction is slipping after three years of strong ratings, as the industry matures. The sector scores declined 2.7% from the previous year, but were better than the E-tail sector scores, which fell an even greater 4.8% in the same period.

"Some of the best-known brands are changing business models and their relationships with customers," says ForeSee Results CEO Larry Freed. "That's hard to do without eroding satisfaction." Amazon and eBay both fell a significant four points from last year.

E-commerce sites must continue to improve in a world where customers continuously expect more, Freed says.—Paula Klein