--- Kim Brennan <kimbrennan@MAC.COM> wrote:
>
> My calculations of margin of error are based on GPS values for speed
> and distance.
>

I have zero knowledge about GPS values for speed and distance. Does GPS
give more accurate measure of speed and distance? I understand GPS is extremely
accurate and reliable to pin point your location and maybe the distance
between locations. But how does it measure the actual traveling distances
between two points? Does it track every foot of your track and add up to
get the total distance you have traveled? Or does it use its software
to add up straight distances of some not too short segments along the route
you have traveled? If the latter is the case then I have to doubt its accuracy.

My house is located near by a school. There is a radar speed detector with
large digital display on the street. I often used it to check my speedometer.
I have found my speedometers of all my cars just about dead on accurate.

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