why is precision important?

Question

why is precision important?
thanks!

Answer 1

Accuracy is how close the recorded value is to the true value.

Precision is how repeatable the recording process is. If something is 2 inches long and you repeatedly get 2 inches on your ruler, your ruler is both accurate and precise.

You can have a precise instrument that records the same thing over and over, but it might not be accurate.

If something is 2 inches long and you keep getting 1.5 inches on your ruler, then your ruler is precise but not accurate.

Precision is important because you want to have instruments that are consistent, but it only works if they are accurate too.

Answer 2

Geomatic is correct: Precision is important, because it is a measure of the repeatability of a measurement. Accuracy is important because it is a measure of how close a measurement is to the actual value.

Consider the example of two dart throwers; each aiming for the bullseye:

One thrower's darts land near the triple 20, near the triple 3 and near the triple 12. All widely spaced; but if you averaged them out, the average throw would be very close to the bull; so you could say that the thrower was accurate.

The other thrower's darts all land in the triple 20; even though he was aiming for the bullseye. His throwing is very precise; but not very accurate. His throwing is suffering from some form of experimental error.

Who is the better dart thrower? On average, you would say the first; but the second is much more precise. But what if you advised the second thrower to aim three inches lower?
Then his accuracy would be the same as the first throwewr (but not more accurate), but he would be also far more precise.

That is why precision is important, and accuracy without precision can sometimes lead to the wrong answer (as can precision without accuracy).

Answer 3

Think about it, what if the dentist said "you have a cavity here, I will just drill around somewhere in the vicinity and eventually I will get it fixed." Personally I would prefer him to drill in the precise spot.