Should investors consider customers satisfaction in the same way they pour over sales?

A small group of stock-market researchers say companies should at least hand over the data. They argue that firms should disclose their customer satisfaction scores when reporting earnings and other financial results because customer happiness seems to be a pretty good predictor of the two things that matter most to stock investors: returns and volatility.

One way to measure customer satisfaction is the American Customer Satisfaction Index, developed at the University of Michigan and first published in 1997. The ACSI, which now covers 225 companies in 45 industries, is based on survey customer results and uses a 0 to 100 scale. The U.S. Postal Service, for purposes of comparison, has a current score of 71, down from 74 last year.

The index is useful for judging entire industries. Airlines and subscription television companies, including cable operators, share a dismal average score of 66. Americans are generally happy with their soft drinks (85), beer (84) and electronics (83). Credit unions (84) are more beloved than banks (75). Internet news shares a meager 74 with cable television news.

Sometimes, the index provides early evidence of new trends. For example, most car makers failed to make customers happier last year, but American firms did better than foreign rivals. As a result, U.S. brands slightly topped Japanese and Korean ones on the index for the first time since 2000 (although all of them trailed European brands).

Armed with a numerical scale for customer satisfaction, researchers have put their computers to work searching for correlations. Customer service measures, after all, have long had clear costs in the short term but less-identifiable benefits in the long term, tempting companies to, say, cut back on staffing at call centers and training in stores to meet profit targets.

A 2006 study published in the Journal of Marketing concluded that "it is possible to beat the market consistently by investing in firms that do well on the ACSI." Since then, studies have found that companies with high levels of customer satisfaction save on advertising (presumably because of the contribution from word-of-mouth marketing), attract more-talented workers and have shares that tend to fall less than the broad market during downturns.

The three companies below have ASCI scores that lead their industries.

Heinz

ASCI score: 89
Industry average: 83

I recently called the Customer Resource Center at Heinz. Carol picked up after just 10 seconds, seemingly eager to help. I didn't actually have questions or concerns about the company's namesake sauces, its Ore-Ida potatoes or its Weight Watchers frozen entrees. I was just curious about whether a person would answer. Heinz shares have bested those of packaged food makers Kraft, Campbell and ConAgra over the past year. All four have done better than the broad U.S. stock market, with strapped consumers forsaking restaurants in favor of meals at home. Heinz shares sell for 15 times earnings and carry a tasty dividend yield of 3.9%.

Nordstrom

ASCI score: 83
Industry average: 75

I'm not sure which is more impressive: that a 2005 book called "The Nordstrom Way to Customer Service Excellence" commands more than $16 a copy on Amazon.com, or that it recently ranked a respectable No. 61,880 in sales among a universe of millions of titles. The book discusses the department store's liberal return policy ("virtually an unconditional, money-back guarantee") and its motivated, empowered sales staff. Nordstrom over the past year has turned 10.6 cents of each sales dollar into operating profit, versus an average of 7.9 cents for clothing stores. The company isn't immune to recession; last year, sales at its longstanding full-line stores fell 7.2%. Last quarter, however, same-store sales rebounded more than 8%. Per-share profits this year are expected to jump 35%. Shares sell for 12 times the current-year earnings forecast and yield 2.8%

Apple

ASCI score: 89
Industry average: 83

My lone experience with Apple customer service went so well it was almost creepy. I had to mail in one of its clever iPhones because of a damaged screen. The company sent a pre-addressed, postage-paid box with instructions on just what to do, and as I was looking for something to use to pop out the tiny memory card that holds my account details, I noticed that someone had thoughtfully included a paperclip for that purpose in the box. Those cost only a penny apiece, but who can find one when they need one? Apple shares aren't cheap, at 17 times earnings for the company's fiscal year ending Sep. 26, but as with the company's gadgets, it's not difficult to talk yourself into paying up for them. For example, subtract the company's $27 or so in cash and short-term investments from its stock price and use next year's earnings forecast instead of this year's, and the price-to-earnings ratio drops below 13.