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Comment by ForTheKidz | Hacker News Reader

As long as any error is consistent, I don't really mind. Mostly I use it as a way to track progress over time anyway.

Exactly. It doesn't really matter.

If your tracker shows you walked 12000 steps today as opposed to 8000 yesterday, even if you actually walked 10500 today and 8750 yesterday, that's still progress.

Yeah. I have noticed that the relative changes in numbers seem to be very correct. I can’t validate the absolute numbers, so I don’t really look at those so much. For the Apple Watch, I’ve noticed that the sleep tracker is quite accurate too, in absolute terms. That is, when I remember having long, wild dreams, I have a substantial amount of REM time. When I don’t remember my partner doing whatever at some hour, I was in deep sleep. If I toss and turn a lot, I see a lot of awake segments. So that part seems pretty accurate.

I recently started using one of these. The other day, I was working out on a rowing machine and received an alert (twice!) that my heart rate was extremely high. I was surprised because I wasn't even pushing myself that hard, and I am a fit person in general.

Upon research and asking around, I understood that it's more of a false positive. A more paranoid person may have reacted differently in such a scenario. So, consistency alone may not always suffice.

Wrist based heart rate accuracy during rowing and cycling is notoriously bad.

All the fitness super-nerds have been using chest straps long before wearables were a thing.

You need the band on your tracker to be very snug or this is likely to happen. You're actually seeing the tracker move, not the heart rate.

I've seen substantial mismatches between wrist and chest strap if my tracker had any ability to wiggle. With an infinitely adjustable metal band set so there's no slack but no pressure I see a good correspondence, although I haven't put it a test as hard as rowing (my activity of choice is hiking.) But my wife absolutely doesn't like such a band, wearing a soft, loose band and using her arms her "heart rate" has gone above 200.

I have also seen an environmental effect--these days I use the chest strap sensor because if my wrist is cold (conditions just below when I would add another layer) the wrist data can go totally bonkers.

That's a good point, thanks.

For the heart such errors are problematic

From what I gather, for fitness and on an individual level, the delta seems more interesting than the current rate.

Yeah. They may not be terribly accurate but if they are precise they can still be useful.

That's not how error percentage works and why do we all just accept that everything has become mediocre?

In what fantasy past has cheap, personal activity tracking a) existed and b) been better?

Could it be better still? Sure, but I see no reason to assume that people are somehow lowering standards and not working on making it both cheaper and better all the time.

The fact that a technology hasn't existed before is not an excuse to sell that technology with an implementation that doesn't work.

I am even OK with selling, but they should drop the usual PR lies and be honest. No business will ever do that though, consumers in general are not that smart/ have good critical thinking.

So I don't see an easy solution apart from governmental regulation. But you need a consistently stellar government for that.

Well we're discussing whether this constitutes "doesn't work [at all]" or "doesn't work [perfectly]."

There are multiple meanings of the word "error".

I just don't care how accurate that the watch is (thus far anyway) because the perception of progress—delusional or no—is why I use it.

Generally, though, my perceived performance is reflected in the relative numbers. If I felt otherwise I too would be complaining about accuracy.

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