the new math: old battle of the lovees was: PDP1 3571

I remember a first year uni. chemistry lab where we had to calculate Avogadro's number using a graticule on an oil slick. I did the error analysis of the results I got and only quoted 6.02 * 10^23 as the result along with the error margin. The post-grad chemistry student acting as tutor didn't get it. Without repeating the experiment hundreds of times (in the two hours allocated), it was unreasonable to quote a more accurate figure.

The accummulation of errors over several measurements; the different physical conditions under which measurements are made - frequently uncorrected - all contribute to 3 decimal places being typical of the reasonable accuracy obtainable unless extremely meticulous measurements are made; experiments are repeated and independently replicated; and statistical technuiques applied to the error analysis.

That's the graduation. What's the accuracy?

Depending on who buttembles gauge blocks, the length defined by them can differ. Even temperature compensation needs to be allowed for; in a non-linear fashion as it can vary about 30% between nominally-identical blocks and over different temperature increments.

When Engineers design stuff for buttembly, they take into account limits and fits; and how they can accummulate (or not) in the building of a product. The bigger hammer isn't usually an option in getting parts to fit.

The machinists that you mention earlier are also incapable of machining to the precision that they can measure. That sucks but they learn to live with it.

Scientists don't get a free ride. Scientists who quote figures with insignificant precision abound. It doesn't actually lend credibility to their work; especially when the things that they seek to prove are in the random scatter of the insignificant digits. -- "Bernd Felsche - Innovative Reckoning, Perth, Western Australia ASCII ribbon campaign "Laws do not persuade just because X against HTML mail they threaten." and postings Lucius Annaeus Seneca, c. 4BC - 65AD.