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** The standard deviation from the arithmetic mean.
** The standard deviation from the known true value.
=Footpod Analysis=
The footpod data was collected with a no calibration in the watch (factor = 1.0), and then retrospectively calibrated. This allowed me to provide both raw and calibrated data. I tried several calibration methods:
* A fixed calibration for each shoe I used in the testing period. This calibration was based on the average of three runs with the shoes.
* A simple average of the three prior runs.
* A weighted average of the three prior runs using weights of 3, 2, 1 for the three prior days.
* The average of the prior day's run.
{| class="wikitable"
! Calibration
! Trueness
(Average Distance Error)
! Standard Deviation
(From mean)
! Standard Deviation
(From true)
|-
| No calibration
| 2.50% (132.2 Ft/Mile, 25.0 m/Km)
| 3.83% (202.5 Ft/Mile, 38.3 m/Km)
| 4.58% (241.8 Ft/Mile, 45.8 m/Km)
|-
| Fixed calibration
| 0.02% (1.2 Ft/Mile, 0.2 m/Km)
| 1.38% (72.7 Ft/Mile, 13.8 m/Km)
| 1.38% (72.7 Ft/Mile, 13.8 m/Km)
|-
| Simple 3 day average
| 0.15% (8.0 Ft/Mile, 1.5 m/Km)
| 2.47% (130.4 Ft/Mile, 24.7 m/Km)
| 2.47% (130.6 Ft/Mile, 24.7 m/Km)
|-
| Weighted 3 day average
| 0.10% (5.5 Ft/Mile, 1.0 m/Km)
| 2.41% (127.1 Ft/Mile, 24.1 m/Km)
| 2.41% (127.2 Ft/Mile, 24.1 m/Km)
|-
| Yesterday's average
| 0.03% (1.4 Ft/Mile, 0.3 m/Km)
| 2.51% (132.3 Ft/Mile, 25.1 m/Km)
| 2.51% (132.3 Ft/Mile, 25.1 m/Km)
|}
=Sources of Error=
There are a number of possible sources of error.
