Pace Accuracy

Mstrlucky74
Mstrlucky74 Registered Users Posts: 13
Legendary Explorer
edited January 24 in TomTom Sports
I know there have been some issues with the accuracy of current pace. But how accurate have others found average pace to be? In the attached pic that would be my average pace, correct? Thank you.

Comments

  • Mstrlucky74
    Mstrlucky74 Registered Users Posts: 13
    Legendary Explorer
    Anyone? Thx
  • icemac
    icemac Registered Users Posts: 199
    Legendary Explorer
    Hi,

    You are correct it is average pace of Your run.

    Cheers, Maciek
  • Mstrlucky74
    Mstrlucky74 Registered Users Posts: 13
    Legendary Explorer
    Thanks. How accurate have most found this to be?
  • tfarabaugh
    tfarabaugh Posts: 16,943
     Superuser
    It is exactly accurate as long as the distance and time are as it is simply distance/time. Whether it matches what shows on the watch during an activity is a different story but this is simply doing match on the totals.

    I hope this helped answer your question. If so, please mark it as a solution so others can look for it if they have the same question.
  • TheOtherPete
    TheOtherPete Registered Users Posts: 24
    Prominent Wayfarer
    Thanks. How accurate have most found this to be?
    Before buying my Spark3 I was using my Samsung G6 phone with MapMyRun to track my runs and for a while I ran with both -- I found that the Spark3 reported significantly shorter distances (and consequently slower avg pace times), e.g. Spark3 would say I ran 9.7 miles when the SmartPhone would say I ran 10.

    Given that the Spark3 is device dedicated for running I assume that it was the more accurate of the two but short of actually running on a pre-measured course I'm not sure how to prove it.
  • xray79
    xray79 Registered Users Posts: 160
    Renowned Wayfarer
    Thanks. How accurate have most found this to be?
    Before buying my Spark3 I was using my Samsung G6 phone with MapMyRun to track my runs and for a while I ran with both -- I found that the Spark3 reported significantly shorter distances (and consequently slower avg pace times), e.g. Spark3 would say I ran 9.7 miles when the SmartPhone would say I ran 10.

    Given that the Spark3 is device dedicated for running I assume that it was the more accurate of the two but short of actually running on a pre-measured course I'm not sure how to prove it.
    Distance measured by any GPS device is different per device on the same run/route. That is because of the fact that the GPS has an inaccuracy of a few %. In general i think the watches are ok with GPS. The actual pace is also ok when you run at a steady pace. Doing intervals will show you that the pace lags a bit.
    Even on a certified Half Marathon last week my watch recorded 21.21 KM But Strava says 21.1. It also depends on the race line and if you walk in woods with cloudy weather reception off GPS might be off and you might miss more meters.
  • TheOtherPete
    TheOtherPete Registered Users Posts: 24
    Prominent Wayfarer
    xray79 wrote:
    Distance measured by any GPS device is different per device on the same run/route. That is because of the fact that the GPS has an inaccuracy of a few %.
    Understood but the question is which device provides more accurate GPS, the watch or a SmartPhone? In my experience the Spark3 consistently gives a shorter distance traveled than my Samsung smartphone. If both are enabled and calling out mile splits I can see the Spark3 drift further and further behind with each mile passed. I'm wondering if the sampling rate is different, hopefully the Spark3 is more accurate.
  • tfarabaugh
    tfarabaugh Posts: 16,943
     Superuser
    xray79 wrote:
    Distance measured by any GPS device is different per device on the same run/route. That is because of the fact that the GPS has an inaccuracy of a few %.
    Understood but the question is which device provides more accurate GPS, the watch or a SmartPhone? In my experience the Spark3 consistently gives a shorter distance traveled than my Samsung smartphone. If both are enabled and calling out mile splits I can see the Spark3 drift further and further behind with each mile passed. I'm wondering if the sampling rate is different, hopefully the Spark3 is more accurate.

    A variance in distance between devices is totally normal. The nature of consumer grade GPS is that each data point collected is only accurate to within 15m-30m of your actual location. We give it a lot more credit than it deserves, it is not exact, it is an estimate. The watch collects the data points and then tries to figure out a route using them (considering that some points may overlap or duplicate) and a corresponding speed. The watch then smooths the data to come up with the most reasonable route taken according to the algorithm it is programmed with. This is why every watch, even two of the same model, will come up with different distances and speeds, as they are collecting different GPS data. Plus if one device has an altimeter and one does not (your phone may but the watch does not) the difference in vertical distance will also impact the totals. Two GPS points collected may be 50m apart from one another on the horizontal plain, but if they are on a steep hill might actually be 100m in actual distance (think of the length of the base of a steep triangle versus the length of the slanted side). Each device deals with vertical distance differently and some do it better than others.
  • TheOtherPete
    TheOtherPete Registered Users Posts: 24
    Prominent Wayfarer
    tfarabaugh wrote:
    A variance in distance between devices is totally normal. The nature of consumer grade GPS is that each data point collected is only accurate to within 15m-30m of your actual location. We give it a lot more credit than it deserves, it is not exact, it is an estimate. The watch collects the data points and then tries to figure out a route using them (considering that some points may overlap or duplicate) and a corresponding speed. The watch then smooths the data to come up with the most reasonable route taken according to the algorithm it is programmed with. This is why every watch, even two of the same model, will come up with different distances and speeds, as they are collecting different GPS data. Plus if one device has an altimeter and one does not (your phone may but the watch does not) the difference in vertical distance will also impact the totals. Two GPS points collected may be 50m apart from one another on the horizontal plain, but if they are on a steep hill might actually be 100m in actual distance (think of the length of the base of a steep triangle versus the length of the slanted side). Each device deals with vertical distance differently and some do it better than others.
    I think both the watch and the phone are doing the same thing in terms of GPS (maybe different sample rates though) so I'm not sure why one would be consistently shorter than the other.

    You bring up a good point about elevation - I don't know if the smartphone is recording that real-time or its just the software (MapMyRun) that is adding that information in after the fact. TomTom's MySports web site also shows elevation for the route I ran so I am betting that is just used to let you know how much elevation you covered, not distance.

    I just did some Googling about the same issue and the consensus seems to be that even if are running a very hilly course the amount of extra distance the hills adds is so insignificant that it is more of a rounding error.

    Shamelessly stolen from http://www.letsrun.com/forum/flat_read.php?thread=2192407

    "An 8% slope would be 8 (feet/meters/yard/cubits...) of rise for every 100 (feet/meters/yards/cubits...) of run.

    Doing simple Pythagorean solution of a^2 + b^2 = c^2 where a=100, b=8, gives us:
    10,000 + 64 = c^2 (where c is your distance actually run up the slope).

    Solving for c gives us 100.3, or a difference of 0.3%

    This means for every mile (5280 feet) measured on the flat when actually running up a steep (8%) slope, you actually ran 5297 feet, or a stunning 17 feet longer. 10 mile run? That's 170 feet difference. You sure you can map anything on mapmyrun to that level of accuracy?"