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Originally Posted by aerohead
Probably depends upon the type of science one is doing.
When I'm 'noodling', I simply leave whatever is on the display, or move it into memory, for future re-insertion, for the duration of the calculations.
It would be 'more' work, and less time-efficient to do otherwise. Not to mention accuracy issues.
When I began formal studies, rolling force coefficients for tires easily ran to ten decimal places. Observed wind tunnel values, up to 4-places.
If you're looking for that 0.005 difference from a radiator shutter, you want as 'tight' an accounting as possible.
You know that it requires extremely advanced statistical analysis tools to even identify some 'trends' which are under scientific examination?
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I have no doubt that the measured value in the wind tunnel was to 4 or even 5 decimal places. However, the published number was to two decimal places.
Agreed, on the tiny change from a radiator shutter, they will do measurements down to 3,4 or 5 decimal places. However, that doesn't necessarily reflect in the published data, if the cD was actually 0.304 and then a radiator shutter was added that reduced the drag to an actual 0.299, the published number is still going to be 0.30.
The difference may be 1.6%, but it would be erroneous to claim that because the initial figure was 0.30 and there is a 1.6% reduction, that the new drag coefficient is 0.295.
Because as we see in the above example the actual figure is 0.299.
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What you should have said is that actually the number observed could be between these two points, which would be odd unless the sensors were not calibrated to a standard.
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You are confusing accuracy of measurements with precision, read about it here
https://en.wikipedia.org/wiki/Accuracy_and_precision.