Textbook! Let me see if I understand… a self-selected sample of walkers and runners, with no randomized treatments at all, is being “plumbed” by “new science” to make generalizations for people who are neither walkers nor runners already….  And then without a blush, the reporter goes on to note that the “versatile” sample is being used to test for differences in all sorts of outcomes… heck, I bet running causes people to have last names that are more likely to start with letters in the upper half of the alphabet… or maybe it’s their first name? Middle name? Name of father?

But on other measures of health, new science shows that walking can be at least as valuable as running — and in some instances, more so. A study published this month that again plumbed data from the Runners and Walkers Health Study found that both runners and walkers had equally diminished risks of developing age-related cataracts compared to sedentary people, an unexpected but excellent benefit of exercise.

via Is It Better to Walk or Run? – NYTimes.com.