Variations between running apps

inigo

Perhaps someone could explain to me why the variations between running apps? I've got a tomtom runner watch (no altimeter), which I hook up to the computer to automatically upload the runs to Mapmyrun, Strava and Runkeeper. I know that different apps will use different algorithms to calculate data so minor differences are understandable. For road runs in the city the differences between apps are small and I'm not bothered about them. But when it comes to trail/hill runs the differences are sometimes crazy. One example:

Watch:
27.17km, no elevation data

Mapmyrun:
27.17km, 927m

Strava:
27.2km, 1078m

Runkeeper:
32.44km, 2083m :rolleyes::rolleyes::rolleyes:

Which one of the above would you say is more accurate?

dna_leri

The first one.

The rest are all estimates, at least the watch won't pretend it can do something it can't.

inigo

Would the watch not be another estimate though? Would it noy have its own algorithm like the apps? That plus the fact that it doesn't have a barometric altimeter would suggest that the displayed distance is just another estimate... Or have I got it wrong?

dna_leri

I thought you just meant the elevation data.
The watch says "no elevation data" that is correct.

On the distance 27.17=27.17=27.2≠32.44 (to within the accuracy of GPS).
It seems clear which one is incorrect.

inigo

Garmin:
27.22km, 1092m

No probs with distance then if I ignore Runkeeper... But the difference in elevation say between Garmin and Mapmyrun is 165m in the example. Which app do people find more accurate?

28064212

inigo wrote: »

No probs with distance then if I ignore Runkeeper... But the difference in elevation say between Garmin and Mapmyrun is 165m in the example. Which app do people find more accurate?

There's no way to know which gives more accurate elevation information for a specific run. One could be spot on, or both could be massively, massively out. They calculate it based on the elevation data they have for particular coordinates, but that can be, at best, estimates. The only way to get even remotely accurate elevation data is an altimeter

inigo

It's kind of annoying that... I'm trying to have a feel for what will be my first marathon (Causeway Coast) and I get differences of up to 500m or so for elevation gain!

Micilin Muc

I wouldn't be too scientific about height gain when training for a hilly race. Judging by the contours given on the Google Map on Terrain View, I would say that your run had something more like 1200m of climbing, which is obviously very decent. Keep doing that kind of run and you'll be sorted.

inigo

Micilin Muc wrote: »

I wouldn't be too scientific about height gain when training for a hilly race. Judging by the contours given on the Google Map on Terrain View, I would say that your run had something more like 1200m of climbing, which is obviously very decent. Keep doing that kind of run and you'll be sorted.

Thanks for the kind words. Always nice to hear them when you're beginner!

BTW, I happen to be a scientist but I was trying not to be one too much, particularly when I'm out running. :rolleyes: I might look into a high-end watch with barometric altimeter now that my birthday is fast approaching. Just to keep the scientist in me entertained.:D