If a picture is worth a thousand words, what can you say about a picture the size of a single word?

Infoguru Edward Tufte has coined the word “sparklines” to describe wee word-sized graphics that pack a lot of data in a tiny package.

Conventional wisdom holds that an infographic — say, a bar chart or line graph — needs to be pretty big to be useful. But Tufte points out that human beings are actually pretty sensitive to fine visual detail, which is why typographers spend so much time worrying about minute variations in the shape of a letter that’s going to appear only 10 points high on the printed page.

A single word of 6 or 7 letters, the average English word length, makes 100 to 700 visual distinctions. Why not construct data graphics that work at the resolution and intensity of detail of routine typography? Thus the idea of sparklines: small, intense, wordlike graphics.

Tufte includes examples ranging from stock prices to a baseball team’s win-loss record to sunspot activity over 175 years. (Here’s something freaky: with the sunspot graphic, Tufte shows how the tiny graphic actually conveys more visual insight than the larger one.)

Think you might have an application for this little tool? Kevin Hale at particletree has a terrific roundup of ways you can produce your own sparklines using anything from Microsoft Office to Flash to WordPress to a web browser.