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Read Thread: W4F, Fitbit, and Register Entries

W4F, Fitbit, and Register Entries
Board: Walking4Fun
Mar 1, 2017 5:05am
Thread (disabled) Board
So today I logged into W4F early and saw that Fitbit synched 13.1 miles for yesterday. As usual I verified this with the Fitbit app and for the first time saw a somewhat significant error (at least for me it was). The app showed that I covered 13.55 miles not 13.1.

So as I scrolled down through the photos, and really enjoyed the cute little pica, and winced at Karolina's bloody toe I got annoyed that all my miles aren't being recorded. So I went back and manually adjusted the miles to 13.55 and W4F gave me 13.6. But now I can no longer see the original register entry I made to adjust that. Not like it's a big deal or anything.

I was just wondering how all that works together. Why the register entries I saw when 13.1 miles were recorded were not the same as when I adjusted it to 13.6 miles for the same day?

Another thing that's starting to bother me with Fitbit as I near the end of the trail. I don't like wasting miles at the end of the trail so I usually add 0.1 miles at the end just to make sure I complete the trail. Any extra miles I walk that day I carry over to the next day to add to the new trail. Cheating? Nah! Just manipulating numbers a tiny bit. I still do all the work. So I'm wondering if I can shut off Fitbit just before completing the trail so I can manually close out the trail and than restart Fitbit synching a day or two into the new trail.
Re: W4F, Fitbit, and Register Entries
Board: Walking4Fun
Reply to: #942422 by BBStacker
Mar 1, 2017 12:30pm
Thread (disabled) Board
The app showed that I covered 13.55 miles not 13.1.

Distances are calculated, not measured. The Fitbit is only counting your steps and that's the only information sent to W4F. The distances on both Fitbit and W4F are calculated based on the stride for your account. If you didn't enter your stride, an "average stride" is used. I don't know how Fitbit estimates your stride, but Walking 4 Fun takes as much information is does know about you which could include gender, age and height then finds the average stride people have entered matching those statistics and uses that.

But in any case, the only way to get distances to match on both Fitbit and W4F are if you manually set the stride to be the same on both websites. They might not even wind up being exactly the same on the two websites due to rounding differences, but those types of differences would likely be minor.

I don't think the distances on one website are any more accurate than the other, though. The steps should always be the same, though. The calculated distances can be very different depending on your stride.

So I went back and manually adjusted the miles to 13.55 and W4F gave me 13.6.

Internally, W4F stores floating point numbers so it would have recorded 13.55 miles. (Actually, it's probably stored as something like 13.55000000001 or something ridiculous like that. Floating point numbers are funny that way.) But for display purposes, I don't want to display a stupid number like 13.55000000001 so I always have it round off to the nearest 10th of a mile--which is accurate for most purposes. =) But the thing to remember is don't sweat the small stuff. Your Fitbit might display distances with a precision to a hundredth of a mile, but there's no way your Fitbit can actually be accurate to that level of precision. If your Fitbit were entirely accurate, it really ought to say something like "13.55 miles--plus or minus 1.55 miles with a 90% confident level."

It's a false sense of precision, which is why I never have W4F display numbers smaller than a 10th of a number. But internally, it stores the numbers with much more precision than that.

But now I can no longer see the original register entry I made to adjust that.

It should show up somewhere. If you adjust the miles, it's possible the register entry is now a day "ahead" or "behind" you on the trail depending on if you added or removed miles, but it ought to be in there somewhere.

Why the register entries I saw when 13.1 miles were recorded were not the same as when I adjusted it to 13.6 miles for the same day?

You should see the same register entries--and maybe a few more for that extra half-mile you added. The register entries from that extra half mile would have been "taken" from the next day's register entries, though, so you'd lose some entries that next day.

So I'm wondering if I can shut off Fitbit just before completing the trail so I can manually close out the trail and than restart Fitbit synching a day or two into the new trail.

You can do that. I think it's probably easier just to let Fitbit sync the numbers, then change them after the fact. The day after a trail is finished and your Fitbit has synced, go in and remove the necessary number of miles/steps from the previous day. After the end of your first day on the new trail, go back and add the steps you removed from the previous day. Just wait for the day you want to adjust to be done and that your Fitbit has already synced all the data from the day before editing the numbers, though, so a sync doesn't overwrite your manually-entered data.

In theory, this should work, but I should mention that W4F will auto-check Fitbit data at something like 5:00 AM from the previous day just in case W4F missed a sync update. It's not supposed to overwrite manually entered data, but admittedly, I haven't tested it thoroughly. If there's a bug in there, your manually entered data might be overwritten. If it does, let me know--I'd like to know definitively if that code works correctly or not. But you can avoid the potential problem if you wait until the afternoon to manually update your step counts of the previous day.

Shutting off your Fitbit link and then re-activing it, theoretically can work, but it could cause similar problems if Fitbit syncs your data from the previous day to W4F and winds up overwriting your manually entered steps.

So I think just editing the steps after everything has synced is easier than unlinking and linking your Fitfit.

Actually, I think it's easier just to let Fitbit do whatever it does and not sweat the small stuff since distances are only estimates anyhow. =) You lose a mile or two of photos after walking of the end of the trail? Well, for all you know, you might not have even walked those miles to begin with if your stride is listed a tenth of an inch too long. *shrug*

-- Ryan
Re: W4F, Fitbit, and Register Entries
Board: Walking4Fun
Reply to: #942442 by Green Tortuga
Mar 2, 2017 4:05am
Thread (disabled) Board
Wow! Very thorough explanation. Thank you.

I dug deeply into the Fitbit App and eventually found the stride they automatically set for me. Surprisingly, it's based exactly on the same parameters that W4F uses. But in Fitbit's case they made my stride an inch longer than I have set in W4F. That may account for the discrepancy. I will re-measure my stride again and adjust as necessary both applications.

You should see the same register entries

I did not! When I first entered a register entry, with the 13.1 mile recording, there were at least five other register entries. After changing the mileage there was only one other register entry and I do not think it was included in the original entries. That's what threw me off on those. I'll poke around a bit on W4F today and see if I see those original entries. But I won't lose any sleep or steps over it.