question for Mapmyrun/walk users

ericcumbee

[img]https://dl.dropbox.com/u/3768052/Screen Shot 2012-07-23 at 8.18.53 PM.png[/img]

i went for a walk sunday night using mapmywalk like i have usually done. mapmywalk said it was 7.8 miles. that track is the one on the left. yesterday i went on running map and mapped it out, it claimed that it was only 6 miles and change. so i did a test last night, i used my phone and my mom's phone and retraced my route in the car with Mapmywalk running. both of them agree with the 6 mile and change measurement (that one is on the right).

im just wondering where the difference came from. the only differences between my walk and retracing the route are that i cut through the park on my walk, and ducked over one street for a block to get water. also on the car retrace i had to get creative on retracing the route because i walked part of the way against traffic on a oneway street.


my leading theory is that since my velocity was faster in the car, my phone used fewer GPS data points and the 7.8 mile number was a result of inaccuracy of GPS building up over a long period of time.


while not that big of a concern i also got a laugh out the calories burned calculation from the retrace. apparently doing 6 miles in 16 minutes is only good fo 96 calories. it makes me wonder if there algorithim for calories burned is really good and figured out that was bad data, or if its really simple and only takes into account duration.

FitToBeFab

I don't know about the calories burned portion (I always seem to trust them more...maybe I shouldn't?) but I've had similar issues with the iMap versus retracing using the "clicking" method. It looked like on your walking map there was a small loop that dipped out - hardly 1.8 miles - but that would still make a small difference.

Also, I think the iMap isn't as accurate sometimes because it's so dependent on the gps satellites and not the actual route you take. There have been times where my iMap said I ran from my house to my friends house (a 25 mile drive) in 20 minutes, and when we actually started our run, it said I had been running for 45 minutes and our pace was a 1:20 mile.

Oh technology.

ericcumbee

I don't know about the calories burned portion (I always seem to trust them more...maybe I shouldn't?) but I've had similar issues with the iMap versus retracing using the "clicking" method. It looked like on your walking map there was a small loop that dipped out - hardly 1.8 miles - but that would still make a small difference.

Also, I think the iMap isn't as accurate sometimes because it's so dependent on the gps satellites and not the actual route you take. There have been times where my iMap said I ran from my house to my friends house (a 25 mile drive) in 20 minutes, and when we actually started our run, it said I had been running for 45 minutes and our pace was a 1:20 mile.

Oh technology.

yeah that was where i ducked over 1 block went up for a block and then back over to the orginal road to get water. hardly 1/10th of a mile.

calories burned seems to be fairly consistent with what MFP says.

rdennisjr

I would bet you had the wifi turned on on the picture on the left (much more jagged line) which can interfere with the GPS data. I've had the same problem with mapmyrun and when I turn of the wifi it works much better.

D

ericcumbee

I would bet you had the wifi turned on on the picture on the left (much more jagged line) which can interfere with the GPS data. I've had the same problem with mapmyrun and when I turn of the wifi it works much better.

D

i'll turn the Google Location Services (Wifi Locations) off tonight and see.