CBS blogging is not a correspondence course offered by the televsion network but rather a time-honored writing formula — Clarity-Brevity-Sincerity — that seems all the more relevant today when too many media compete for the attention of people who have too little time.

Thanks to rhetoric professor Richard Lanham for including that nostrum in his book, “The Economics of Attention,” from which I’ve extracted other lessons in previous postings.

How brutal is the struggle for attention? Consider the rule that web guru Jakob Nielsen offers in “Prioritizing Web Usability,” the new book of which he is the co-author. “People spend an average of only 27 seconds on each page, mostly skimming for links and other visual clues about where to go next,” Washington Post columnist Leslie Walker writes in her review of the book.

Speaking of info-skimming: In a survey of newspaper readership in 87 metropolitan markets The Media Audit reports that the percentage of people reading the front page of the paper increased from 51.4 percent to 53 percent between 2000 and 2005. But readership of 11 inside sections declined by varying degrees. The report says movie, travel and lifestyle sections were particularly hard hit. Other inside sections lost about a percentage point of readership.

Apparently more people at least glance through the front section of the paper to get a sense of what editors consider to be “news” — but fewer readers are reaching inside to spend time with their old friend, print.