The number of digits on a display is related to "finesse" or "resolution", not accuracy or precision.9/quote
Alan, thanks for your bomb analogy and for this post. I think to people outside engineering and related fields the industries' meaning of precision in measurement must seem strange.
Fascinating.
"NO, it is less accurate." Using the standard mathematical definition of "precise" (the only sensible one in my view) it is less precise, as it gives the results to only one decimal place, whereas A and B give it to 2 decimal places.
Forget maths. Forget most (not all, as I have shown) of the dictionary definitions. Precision in engineering measurement isn't about how close the results are to the actual (real) value (that's accuracy), it's about their closeness to each other, as illogical as that may seem.
Alan has given both a simple analogy and a more complete answer. But let's look at precision and why it's important.
We are setting up two production lines to produce metals ball,. The size is 10mm (Alan, I'm ignoring tolerance for the purpose of this analogy). Each ball is measured at the end of the line by measuring equipment.
Prior to starting the line the engineer sends through sample balls that measure exactly 10mm to test the measuring equipment, and notes the response
Line 1 measuring equipment gives the following results: 10.05, 10.05, 10.05, 10.05
Line 2 measuring equipment gives the following results: 10.03, 9.98, 10.01, 9.97
Neither measuring equipment is fit for purpose, but we know that line 1 is less accurate than line 2(it measures 0.05 greater than the actual dimension), but is more precise (all the readings are the same). To correct this, the engineer tweaks a resistor or turns a screw. He/she knows that once the adjustment is done the results will be both accurate AND precise. ie. He/she knows that any ball not 10mm will be rejected.
Line 2 is more ACCURATE, because each one of its measurements is closer than 0.05 to the actual dimension. But the results are not consistent and so they have LESS precision. What is the engineer to do? No amount of tweaking will give him the precision (repeatability) he requires. He will never know if the machine will reject 10mm balls because the measuring equipment says they are 9.98 or 10.01, when in fact they are actually 10mm.
P