The number of steps indicated by the iPhone pedometer is 21% less than the actual number of steps by a maximum, half of the cause is "how to use"

The iPhone's "Healthcare" application and "Activity" application have a function to count the number of steps walked that day, but in reality it is often counted less than the actual number of steps depending on how to use and how to walk It turned out.

Smartphone health apps miss some daily activity of users
https://news.ubc.ca/2017/12/06/smartphone-health-apps-miss-some-daily-activity-of-users/

University study shows iPhones can miss 21% of your steps - but half of it is your fault | 9to5Mac
https://9to5mac.com/2017/12/07/iphone-steps/

This fact was revealed by a survey conducted by a research team at the University of British Columbia in Canada. In the research, it is statistically clarified that errors are generated depending on how to walk and how to use the iPhone, verifying how accurate the dedicated pedometer and iPhone's pedometer show data are the same or different . The research team actually walked the participants who participated in the experiment and investigated the divergence of the number of steps displayed by the pedometer and the iPhone respectively. Subjects have both a pedometer for wearing on the waist and an iPhone, and they are walking at multiple speeds on a treadmill.

The result is also summarized in the following movie.

How accurate is the iPhone's pedometer at counting steps? - YouTube


As a result of the research, the case with the least error was around 5 km / h at "speed when walking", and the error of the pedometer and iPhone's numerical value was within 5%. This error is of a level that occurs even with a dedicated pedometer, and it is a good level that it can be accepted as a virtual error margin. On the other hand, however, it was confirmed that when walking at a slow pace of about 2.5 km / h, the error expanded and the opening was 9.4%.


Furthermore, it was the case that the actual error of life was opened, when it reproduced the actual life pattern. According to the results of the research, it was found that 21.5% less number than the actual number of steps, and an error of 1340 steps per day on average.

There may be some people who are aware of it anymore, but the cause is "I do not always have an iPhone." The number of steps when I leave the desk to go to the toilet and go to the coffee creation is surprisingly large, but this is not counted, so the number of steps is shown different from the actual.


However, the point that this error is almost certainly shifted to 'lesser' may be a safe material. Since not the number of steps actually not walking is counted, it seems that there is no mistake if you think that "In fact it should have walked a bit more." In case of more precise measurement, it is OK if you wear a dedicated pedometer with high accuracy as done in the experiment. Or Apple Watch is also effective for improving accuracy.