run tracker software

each time i run (or walk) i cover the same six laps... and each time the gps guided run tracking software tells me i've covered a different distance... the total distance is somewhere between 3 and 3.5 miles... and the software has a 0.7 mile margin of error... at least a 20% margin of error?... it's useless... and that's frustrating...

i've tried five different pace tracking apps and they are all the same on this point... they cannot accurately or consistently measure distance, which makes all the other calculations they provide invalid... one day the tracker software says 3.55 miles and the next is said 3.07 miles for the same six laps... so either the gps has way too large a margin of error to be useful or the laws of physics do not apply to me when i am running...

today, for each lap (in miles) it recorded: .49, .54, .65, .58, .61, .67... the distance per lap discrepancy, as expected, is similar to miles but even more telling... .79, .89, 1.04, .93, .98, and 1.09... same laps, measured up to .3 km apart... so how does this software measure the same lap with such drastic inaccuracy?... i am sure the manufacturer would have some pseudo-scientific response, but as they say on sports center, come on man...

looking at the map the software provides may show the problem... the flaw that appears to be causing the discrepancies in distance and that is the tracker seems to be over-reading (for lack of a better term) one or two step variations along the same path and adding considerable distance to the lap distance because of that... the path track has me crossing streets and going through buildings (impossible) way off the path i walk/jog on some laps so the gps sensitivity and accuracy is way off... i suppose this sort of tracker might be more helpful on a trail run, but it shows serious flaws and inaccuracies on a lap run which would lead me to question the accuracy of distance (and all other stats except the actual time) on any run tracked with a gps... unfortunately the other software i've tried is no different and shows the same gps variations, flaws, and inaccuracies...

so the app i chose because it provided the most numbers (mile times, average speeds, maximum speed, calories burned, and a lot more in miles and in kilometers) because the stats are fun for me and they are motivation to continue improving... but the numbers are pointless because the app cannot accurately measure distance...

so in the end, don't trust a run tracking app for any stats that any stopwatch can give you... the advantage of the app is that it will save the workouts for you, but better chronograph watches will do the same... the phone apps are cheap or even free, but they require carrying the phone with you and pressing the screen (after pulling the phone our of sleep mode) with every lap... a good chronograph watch makes much more sense... so we live with what we've got and the bottom line for runners looking for numbers to help motivate improvement is the uncalculated lap times, the overall time, and the physical assessment by your own senses/feelings...