As impressed as I am by 7-Eleven's (NYSE:SE) same-store sales announcement today, I really don't like the hoopla that surrounds same-store sales numbers. I like the statistic and I like that retailers from The Limited (NYSE:LTD) to Starbucks (NASDAQ:SBUX) all report the metric, but I dislike the weight that the market places on one month's same-store sales results.

Where I really find same-store sales numbers useful is over a period of months or years where trends can be formed and analyzed. This is where a lot of the changes that have been made at 7-Eleven in the last couple of years are starting to shine through.

The revenue growth coming from gasoline sales is simply amazing from a numbers perspective, but a bit disconcerting due to the total volume of gasoline sold being down 0.7% versus April of last year. It's easy to get caught up in the headlines surrounding gasoline sales, but gasoline sales are most important for 7-Eleven when they are accompanied by sales of the company's new and improved coffee, sandwiches, and other offerings.

On the merchandise side of the business, which includes food and beverages, same-store sales were up an impressive 5.7% on top of last year's 8.2%. Such strong gains further demonstrate that the translation of processes and ideas from 7-Eleven Japan is bearing fruit. It's all the more impressive, because gains like this are tough to come by in any line of retailing. 7-Eleven's ability to keep this momentum going through the rest of the year is the real key, but based on my personal shopping habits in 7-Elevens throughout Japan, I have a strong feeling that the sales increases here in the U.S. will stick.

I wouldn't be surprised to see 7-Eleven continue to build on its success simply because the company has a much better competitive environment to work with here in the U.S. than in Japan, where competitors Family Mart, Lawson, and Sunkus have developed stores based on many of the same sales practices and have claimed prime locations.

At first glance, 7-Eleven shares look a bit pricey with a forward P/E of 21. After all, we're talking about unglamorous convenience stores here. But given the company's robust growth, the strong P/E multiple is really just a sign of investors starting to realize the growth potential that is still left in the business and the shares.

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Nathan Parmelee owns shares in 7-Eleven and Starbucks.