The Background

I recently bought a Nike+ GPS Sportswatch (Dec 2012) and started to see some irregular results in my data - as much as 20% of the distance. I started to investigate.

Not only was the distance way off what other peoples Garmins reported, their website 'data' seemed to be more accurate than their website stats they were reporting.

Note that I had applied all firmware and software updates to the watch / computer, and also did all runs using the foot pod.

Find below two links, one is to the original investigation I did, with results, and the other to a Nike GPS testing tool I've wrote. Hope it helps shed some light onto the situation.

The Distance Testing Tool

How To Use This Tool

• Load up your activity detail page from the Nike Plus website. It will look something like:
  http://nikeplus.nike.com/plus/activity/running/<yourname>/detail/1234567890
• View source of the page.
• Find this variable (usually around line 370 - 400 ish):
  window.np.baked_data
• Copy everything from the first brace '{' to the end (dont copy the semi colon). Ie something like ..
  {"activity":{"name":"RUN ON: 12/18/12 06:13 PM","activ ......... metricType":"WORKOUT_BASED","targetValue":3}]}}
  It will be a really long string (depending on run time)
• Paste into the box below