[time-nuts] Problems with Garmin - maybe we should cut them alittle slack
William H. Fite
omniryx at gmail.com
Mon Jan 3 02:31:48 UTC 2011
Thank you, Horst, for your voice of calm reason.
The point that I raised (or tried to...) was that no data base of this size
is capable of being error free, whether the unit cost of production is ten
billion dollars or ten cents. Random error can be reduced but it can never
be eliminated. Worse, we can never know for certain how much exists. cf.
any first year statistics text.
Process engineers--and I'm sure that Garmin has many--devote their careers
to reducing error, both systematic and stochastic. By the time a map
product gets to market, most of the systematic error will have been
removed. More in the $100K maps and less in the $100 maps. It is not
nearly as simple as the cost-per-unit-production model that John posits.
I'm sure he realizes that quite well and was simply trying to make his
But here's the hitch: No matter how hard those eager men and women work at
it, they will never remove all the stochastic error, partly because, as I
noted, they don't know how much is there. Because stochastic error is
random, the errors form a gaussian distribution with a mean of zero. This
enables us to *estimate* the error and make allowances for it, but not to
eliminate it. Would that we could...
Precision, in process control, is often defined as the standard deviation of
the stochastic error distribution. That, too, can be improved but never
So...when people rant about error resulting from shoddy workmanship or lack
of caring...well, maybe. But no matter how careful the workmanship or how
dedicated the craftsmen, the work will not be error free. If that error
lands in the lap of your GPS as you seek the nearest Walgreens, you simply
have fallen prey to what one of my old profs called Tuvshitzki's Theorem.
Horst's point is equally valid. Garmin sells it because for the vast
majority of users, it is plenty good enough and making it better winds you
up on the wrong side of the diminishing returns curve. That's the
Don't look at me, I'm not a capitalist.
The world runs on Garmin gear and Navteq maps. Much of the DoD relies on
Garmin gear and Navteq maps. But if they aren't good enough for some of you
gentlemen, the answer is simple: Don't use them.
On Sat, Jan 1, 2011 at 12:04 AM, Horst Schmidt <horsts at iinet.net.au> wrote:
> first, a happy and hopefully healthy New Year to all of you.
> I think, some of you are going slightly overboard, in what you expect a
> $150 Dollar car navigator should do,
> I also don't believe some of you you realise what exactly it was designed
> to do.
> It is not a device to accurately shoot a missile trough somebodies toilet
> window and hit a specified turd in the bowl.
> It is designed to get you relatively easy and close to a specified
> designation. preferably when used in a motor car
> This it does perfectly well. It may be a few meters out from an exact
> house number, but it got you there without you having
> to look at the map, (or worse get your spouse to read the map and navigate
> It improves the road safety, especially at night time, when you often don't
> see the street names and have to slow down to a crawl
> with a lot of cars bunched up behind you.
> The mind boggles if some of you think because the GPS is not 100% accurate,
> The Fire brigade gets either lost, or tries to extinguish the
> house next door to the burning one, just because the GPS is 30m out.
> What you're actually are saying is: The Fire brigade is full of idiots.
> To sell an item for 150 or so Bucks, on can not reasonably expect it to
> be as perfect than another item which sells for 100 grand or more and
> except a few government institutions can afford it.
> Not every instrument is mad by Agilent for a cost which is prohibitive to
> the normal punter.
> Just get back down to earth, a few years ago you had to learn how to read a
> map, or follow the often useless instructions somebody else gave you.
> Now for hardly any money, you get to your destination with least amount of
> effort and a lot saver than before.
> Regards, Horst
>> "A GPS is a precision device.
>> A Navigator is a consumer device.
>> To confuse the two is to fail to understand either."
>> A navigator IS a GPS. Surveying GPSs may use carrier phase tracking or
>> whatever to get about 2mm accuracy. Just because it is optimized for
>> of location accuracy and gets about 3m accuracy doesn't mean that a
>> isn't a GPS.
>> Note that map accuracy has nothing to do with GPS receiver accuracy. Also
>> some mapping data has built in errors or incorrect POIs to identify the
>> data in
>> case it is copied. For instance, one company's street mapping software I
>> had, in the small town I live in, a POI that said: "***** Institute Of
>> even though there has never been a school there and it was a actually
>> closed gas
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