ALLOCATING SCARCE RESOURCES. The editorial board at the Chicago Tribune gets the point.

The task force's recommendation [that women first schedule mammograms at age 50] is based partly on its finding that annual screening of women in their 40s prevents one death for every 1,904 women tested, compared to one for every 1,339 tested annually in their 50s.

Otis W. Brawley, M.D., chief medical officer of the American Cancer Society, said the task force "is essentially telling women that mammography at age 40 to 49 saves lives, just not enough of them."

Women and their doctors worry that insurers will balk at paying for mammograms on grounds that they're not cost-effective, leading to questions about whether the new guidelines are about improving health care or saving money. If they encourage doctors to be more selective about which patients need frequent screening, they might actually do both.

That's the benefit-cost principle, and if you consider an analogous choice, improving traffic safety or saving money, it's precisely what all highway departments do in deciding where to place four-way stop signs, or build rotaries, or install traffic signals.