I have done two simple tests with 3 clocks, ancient PC, old PC, and my handheld Robic stopwatch. I would suspect that the Robic stopwatch is the best because it is dedicated to being a stop watch while the PCs are just computer clocks. I don't know though.
I thought about it for a while. What we do for Bicycle Time Trials is that we set all stopwatches and the start clock (one of these:
http://www.electronumerics.com/raceclock_lm.htm) about 1/2 hour before the first rider is off to the same time. Then the judges go to the finish line (typically 1/4 to 1/2 mile away) and record the finish times of the riders who go about a total of 10-15 miles based on their stopwatch. So, if the start clock is bang on, but the computer clock that we use to find the finish time is "slow" or looses time, then the last rider gets a small "bonus". (I think I got the signs all right.
)
But I have no idea which clocks are accurate and which ones are off by a bit. At this point, I think it really isn't important..... Until we have a National Event.
Thanks,
Mike