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Cnet’s Smartwatch Step Count Accuracy Test Uses Flawed Methodology

When choosing a fitness tracker, or smartwatch, most people go for style of features other than the actual fitness tracking. Very few reviews seem to think that accuracy is important; I’ve found that many fitness trackers are inaccurate, and I was very pleased to see that Cnet did a test of fitness trackers and smartwatches, comparing them to the Apple Watch.

Unfortunately, the methodology used is flawed. The article says:

“With those caveats in mind, I developed a testing methodology to try and reduce variables as much as possible. I wore each activity tracker or smartwatch on my left wrist at a single time and walked on a treadmill for a mile (as measured by the treadmill’s built-in distance tracker). I then compared the mileage from the treadmill to the mileage recorded on the watch. This test was performed three times with each device I tested to ensure accuracy. The same treadmill was used for the test, and I walked at the same speed (3.5 mph, which came to about 17 minutes each time).”

Most fitness trackers do quite well on treadmills; it’s easy to count steps in a situation like that. It’s much harder to count steps in real-world situations.

When I reviewed the Fitbit Charge, I found that it was very accurate on a treadmill. Compared to the Fitbit One – probably the most accurate fitness tracker, because of the fact that you wear it on your belt – I found the two to be very close:

“Both devices recorded nearly the same number of steps on the treadmill (2,048 steps for the Charge, and 1,997 for the One)…”

But let’s look at the entire paragraph that quote is taken from:

“Here are some examples. One day, I tested the devices by wearing both of them. I went about my usual business, and I walked on my treadmill for 30 minutes. Both devices recorded nearly the same number of steps on the treadmill (2,048 steps for the Charge, and 1,997 for the One), but for the rest of the day, the numbers diverged greatly. Near the end of the day, when the Fitbit Charge was at 5,000 steps, the One was almost exactly at 4,000 steps. These convenient numbers make it very easy to calculate the discrepancy between the two devices. If you take away the 2,000 steps on the treadmill, where the devices nearly matched, the Charge recorded 3,000 steps, and the one 2,000. In other words, the Charge is recording 50% more steps than the One. (I’ve noticed that the Charge records some steps when I’m asleep; a half-dozen here, a dozen there, adding up, some nights, to 50 steps or so. And, no, I don’t sleepwalk.)”

So, comparing the two by only looking at a treadmill test, they look like they’re very close. But comparing the two throughout a full day’s activity, the Fitbit Charge recorded 50% more steps than the Fitbit One.

So it’s good that Cnet decided to test the accuracy of fitness trackers and smartwatches; it’s a shame that they didn’t come up with a valid test.

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How to Turn Off Heart Rate Recording and Fitness Tracking on the Apple Watch

There are a lot of problems with Apple Watches and their heart rate sensors. I’ve written about my experiences, and many websites are reporting this too.

A reader asked if it’s possible to turn off the heart rate recording; the reader doesn’t care about using it, and wants to save battery power.

Watch motion fitness settingsIf I recall from the setup, you are asked at one point if you want to turn it on. But finding the setting later isn’t easy. You’d think it would be in the Apple Watch app under Health or Activity, but it’s not.

To change this setting, open the Apple Watch app, choose Privacy > Motion & Fitness. You’ll see an option to turn on or off Heart Rate, along with another for Fitness Tracking. If you don’t plan to use your Apple Watch for tracking fitness, it’s a good idea to turn both of these off; your battery will last longer.

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The iTunes Guy Looks at Fixing Some of iTunes Match’s Quirks, and More

itunesguy-thum-100004188-gallery.jpgI don’t know how many people use iTunes Match, but I get a fair number of questions about this subscription service. This week, I answer three questions about iTunes Match. I also explain how to add detailed artist information to tags in iTunes, and discuss that Purchased playlist that shows up every time you buy something from the iTunes Store.

Read this week’s Ask the iTunes Guy at Macworld.

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5 Tips to Help You Become a Dropbox Power User

If you’re one of the millions of people who uses Dropbox, you know how convenient it is to have lots of files in the cloud, accessible to your computers, phones, and tablets. One reason Dropbox is so popular is because it’s easy to use: on a computer, just put your files into a folder, and they sync automatically. On an iOS or Android device, a simple app lets you access and download or share files.

But if you only use the basic syncing feature, you’re missing out. In this article, I’m going to show you 5 tips that will help you get more out of Dropbox, and turn you into a Dropbox power user.

Read the rest of the article on the Mac Security Blog.

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The Apple Watch and Resting Calories

I’ve highlighted how the Apple Watch isn’t very accurate as a fitness tracker, and I’ve shown that my Apple Watch’s heart rate sensor doesn’t work correctly, which is leading Apple to exchange it.

But one thing I find surprising is the way the Apple Watch – or, more correctly, the Activity app on your iPhone – calculates resting calories. This is another term for basal metabolic rate, or BMR, the amount of energy your body expends just to keep you alive. If you did absolutely nothing during a day, other than sleep, your body would still burn a certain number of calories. In fact, your active calories only represent a small part of the amount of energy you use.

Like many such measurements that are difficult to measure, the BMR varies according to the way it’s calculated. But one such calculator tell me that may BMR is 2008 calories. Another one, at myFitnessPal, tells me my BRM is 1894 calories.

Resting caloriesNot Apple. According to the Activity app, my resting calories for the full day yesterday was 3184, or 50% more than a BMR calculator. As such, the Activity app tells me that I burned 3829 calories yesterday, with 645 of these being active calories. Yesterday, I took two brisk walks: one on my treadmill, for 30 minutes, which counted as 178 calories, and one outdoors, for about 20 minutes, which clocked 83 calories.

It’s interesting that the 20-minute outdoor walk only counted for about half as much as the 30-minute indoor walk, which measured calories based on my heart rate, and, presumably, the frequency of my steps.

No matter how you slice it, these numbers are wrong. I’ll give Apple a pass on the active calories; there’s no way to get those numbers down precisely. But the BMR, or resting calories? I’ve entered my data in the health app – age, height, weight and sex – so, unless online calculators are way off the mark, Apple has some tweaking to do.

What’s also surprising is that this number isn’t the same every day; it ranges from 3172 to 3195. This is a fixed number, that has nothing to do with my activity. There’s not a big difference between the top and bottom of the scale, but they should be the same every day. Only the active calories should change.

And this is particularly worrisome. This number is based on a very simple calculation, and isn’t skewed by the way you move your arms, or your stride when you walk. It’s the one number that they should get right.

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Kirkville

Writings about Macs, music and more by Kirk McElhearn