A recent NY Times article reviewed a JAMA study looking at the 10 new devices geared at measuring activity. Better Fitness Through Your Phone

N of 1: As a personal aside, since I know that big brother (ie. my phone) is watching and I want to compare favorably to my wife, I definitely am taking more steps and using the stairs a bit more.

Here’s an excerpt:

The pedometer and the accelerometers were generally quite accurate, but one of the wristbands, the Fuelband, underreported the number of steps the volunteers had taken by more than 20 percent.

Others of the monitors were more accurate but, by and large, no more so than the smartphone apps, which cost much less and would likely be more convenient for many people.

The upshot, said Dr. Mitesh S. Patel, an assistant professor of medicine at the University of Pennsylvania who oversaw the study, is that smartphones could offer “an easy, less expensive, but still accurate” means for people to track their activity.

But the broader issue, as Dr. Patel and his colleagues pointed out in a related commentary published recently in JAMA, is that no fitness tracker of any kind has yet proved able to motivate people disinclined to exercise to start moving