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The iPhone Isn’t Accurately Tracking Steps, Says UBC Study

Smartphones are failing to accurately track active minutes in a day, according to new research from the University of British Columbia.

A UBC study found the iPhone’s built-in pedometer that tracks steps in the phone’s Health app misses on average 21.5 per cent of steps a day compared to a purpose-built accelerometer used for tracking.

The findings were gathered after tracking study participants’ activity over three days, discovering the iPhone didn’t register on average 1,340 steps a day—a number that could be the make or break when it comes to hitting the wide goal of 10,000 daily steps.

But the authors argue there are wider implications too. The data collected from smartphones and health apps—including those by Apple—are being used by medical researchers.

“In order to make accurate conclusions, we as researchers need to know that the data is actually representative of real behaviour,” said Mark Duncan, the study’s lead author. “That has major impacts in terms of patient care, and in terms of developing new and better research in the field.”

The university’s study did find that an iPhone’s tracker performed reasonably well in short walks on a treadmill. Their research showed that the slower the speed walked, the greater the per cent in inconsistencies with the accelerometer. Walking at faster speeds, the iPhone’s pedometer was on par with the electromechanical device.

“The accelerometer in the iPhone actually does a pretty good job when tested under lab conditions,” said senior author Guy Faulkner. “You just have to have it on you at all times.”

But outside of the highly controlled environment, it can miss more than one in five of a user’s steps throughout the course of a regular day.

The authors caution researchers on relying on smartphone data for accurate health data but said activity tracking apps are still great for motivation.

“For people who are already tracking their steps, they can rest assured that if their phone says they’re getting the recommended 10,000 steps in a day, they are probably getting at least that many, and they are working toward better health,” said Duncan. “From a public health point of view, it’s better that it underestimates than overestimates.”

The study did note that some of the 33 participants may have forgotten to carry their iPhone with them on short journeys during the three-day experiment, like on trips to the bathroom or answering their door.

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