Lies, damned lies and GPS data.

[sTrongFuse]

I have worked out a "5k" route which I have run a number of times. When I say it's 5k, that's what the GPS tracker in my watch and Garmin Connect tell me it is. I've run this route a few times and, to within a few metres, I always finish in pretty much the same place.

Today, because it's a rest day, I decided to walk it and record it. Each of the first 4 kilometre splits occurred more or less where I expected them to. They were slight differences but mostly I put this down to the fact that I'm usually going past at a slightly faster pace and I'm not generally paying full attention to my whereabouts when my watch buzzes to tell me I've clocked a particular point. That aside, however, they were I expected them to be.

The final kilometre is where it got interesting. When I got the notification, I was still a good 250m from where I get it when my run ends. The cumulative margin of error for the previous 4k may have accounted for 50m of that difference, but not all of it. I do tend to run the last 500m slightly faster than the rest, but not enough that I think it would throw up that much of a margin of difference.

I'd noticed before, that a parkrun I did was, according to my tracker, only 4.7k. Given that I imagine the organisers measure these things pretty accurately (trundle wheel?), I assumed that the "error" was on the part of my tracker and not the course being too short. Today's experiment would seem to bear that out.

It does, however, make me wonder what my actual 5k time is, if I'm actually running about 5.25k whenever I do my own routes.

[backintime Graduate]

My tracker (on my phone) lies to me too. I think it hates me. When I did the famous W5R3 it didn't even notice I was running and sometimes doesn't count things and one time it counted me as cycling when I was just mowing the lawn (walking behind my push mower). I think it's probably being unfaithful and seeing someone else and giving them my steps *sob*

[MuddledGardener Graduate in reply to backintime]

Bahahaha 🤣🤣🤣🤣🤣

[sTrongFuse Graduate in reply to backintime]

When I used to just use my phone it was dreadful. I think it just woke up periodically and guessed.

My watch is much more accurate, but even if has its moments.

[2718281 Graduate in reply to sTrongFuse]

My tracker thinks I'm cycling sometimes when I'm driving, even in the motorway!!!

[AlMorr Ambassador Graduate]

I find Mapmyrun/walk pretty accurate, I ran a officially recognised 5K course last October, this same course is used for our local 5K Santa Dash in December but when I ran it I would say that Mapmyrun was around 98%accurate, it told me I was at 5K aroundabout 25 metres short of the December run, there again I noticed that the organisers changed the 3K to go point also about 25 metres as well, we can't all have official Olympic style timers, they would cost a fortune.

[sTrongFuse Graduate in reply to AlMorr]

I have an old phone kicking about that my watch isn't linked to. I might try my next run recording on both my watch and the phone independently of each other. It's a bit sad, I know, but it gives me something to ponder while I'm lolloping through the East Lothian countryside...