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Why the New York Times GPS running article missed the boat	

Yesterday the New York Times published in print and online a rather bizarre article on GPS running watches, one that essentially concluded that they were an �unreliable running partner�.  Now my goal isn�t meant to defend GPS watches, but rather clarify a lot of oddities and inconsistencies in the piece, and why I believe the New York Times missed the boat entirely.

Not all watches are created equal

The article starts off describing the basic features of most GPS watches in the market, such as displaying pace, distance and time � all of which represent the primary reasons that most people pickup a GPS enabled watch.  From there the author goes into a singular test case where she and a friend met up on a run this past Sunday in the following scenario as a basis for much of the remainder of the article:

The challenge here is that I�d ask first � what were the watches in question?  What brands, devices and software versions?  For example, was the one that was off by .42 miles (97.3% accurate) an older model from 5-6 years ago, or was it more recent?  Who made it?  What firmware version?

In the world of GPS watches, the reality is that not all devices are created equal.  As I�ve shown before in four posts of accuracy tests, some units do simply perform better than others.  Sometimes that is correlated to price, and other times it�s tied to the GPS chipset used and/or the firmware.  To base the entire article (and all GPS watches in general) on what appears to be a single watch on a single run being off seems a bit of a stretch.  For example, when the Timex Global Trainer first came out, there were indeed accuracy issues with it.  On average, it was 2.5% off (short) � was her watch a Global Trainer?  Or perhaps, it was an original Garmin FR610 � which also had issues early on with some routes showing about 2% short.  Yet, both have been fixed by their respective companies (June for the FR610, August for the Global Trainer).

I found it strange that the author didn�t note the brand, nor contact them for an official reason, explanation, or PR response.  Isn�t that the most basic journalistic thing to do?

In my mind, this is no different than saying �cars are unreliable�, because your particular car is in the mechanics shop.  As in fact the author noted, her friends route was just about spot on, within .08 miles after 19 miles � or 99.58% accurate.

And finally � there is of course the very real possibility that something might have simply been wrong with the unit, either temporarily or permanently.  For example, on some older Garmin units, sometimes the unit will get stuck on a particular satellite set that will cause significant distance inaccuracies (i.e. a mile or more off).  These are easily fixed through a soft reset, which clears the satellite cache database and forces the unit reacquire the satellite information upon starting up the next time.  No electronics device is perfect, and while this isn�t common, it�s also easily fixed in two button presses and about 10 seconds of time.

Misunderstandings about race distances

The article then segues into a discussion on running race participants and having incorrect distances shown.  It talks with one of the Race Directors for the Rock n� Roll Marathons, regarding complaints that users often have about courses.  This ultimately ended up with this snippet on accuracy:

This is actually a really interesting quote, but not for the reasons you�d think � and this is where the author shows a lack of research.

See, in a race scenario, it�s nearly impossible for a GPS unit to be short.  The most common scenario is for a GPS distance to be long.

Why you ask?

Well, because GPS measures distance in a series of points, usually about 1-second apart.  This means that with the exception of trail runs where you have a slew of switchbacks, it�s virtually unheard for GPS to be short�unless the course itself is short.

And in general when you have multiple people saying the course is short � it usually really is actually short.

See, most long distance road races with large crowds aren�t going to have switchbacks in them, and very rarely do they have a significant number of 180* turns (due to overcrowding) � turns that even if they missed a data point here or there, wouldn�t account for a third of a mile.

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