In scientific experimentations, these two go hand on hand and its often hard to tell them appart, can someone provide a few examples of these? And what is "true value"?
2006-09-08 22:16:15 · 4 answers · asked by geniusflightnurse 4 in Science & Mathematics ➔ Chemistry
Accuracy is how close you were to your goal, on average.
Precision is how consistent you are.
The best example I can think of, in a practical sense, of Precision vs Accuracy concerns firearms.
Let's say you are shooting a 15 round magazine at a typical circle-style target. Obviously you're aiming for the very bull's eye.
You empty your clip, and you now have 15 holes in your target. They are all scattered around the third ring, about the same distance from the bull's eye, but not very close to the center. If you were to take an average of all these holes, your 'AVERAGE' shot would be near the bull's eye. This means you are accurate, but not very Precise. This will make more sense after describing Precision.
New target, new mag. You empty your magazine, and have 15 holes.
ALL 15 holes are within three inches of each other, but in the far upper left corner of the target. You pull up every time you fire. They are NOWHERE near the Bull's Eye...but every single shot was very close to the other shots. This is very PRECISE, very consistent, but not very accurate.
Now, 'true value' is more of a mathematical term, and hard to put into a practical setting.
A set of data points can show you trends, values at specific points, etc. Let's say you're working out an equation, and all your data indicates that the best fit equation is: Y=X.
Some of your data points include:
(1,1) (0,0) (2,2) (3,3.5) (4,4) (5,5) ...
Obviously (3,3.5) is wrong. At X=3, Y should equal 3. This means that the TRUE VALUE of X=3 is Y=3...but the OBSERVED VALUE of X=3 is Y=3.5
Errors in measuring methodes, calculations, environmental factors all contribute to an error in any experiment. The TRUE VALUE represents what the Dependant variable SHOULD BE, even if the observed data is slightly off.
2006-09-08 22:44:26 · answer #1 · answered by Matt 2 · 1⤊ 0⤋
Precision = The quality of being reproducible in amount or performance
Accuracy = The quality of being near to the true value
True value = The reference.
2006-09-08 22:20:59 · answer #2 · answered by Lord Of Lust 5 · 1⤊ 0⤋
precise is accurate
accurate is precise
they're definitely synonym
check the thesaurus
2006-09-08 22:28:12 · answer #3 · answered by angelleah12 2 · 0⤊ 0⤋
wikipedia has a perfect analogy to help you understand the concept:
http://en.wikipedia.org/wiki/Accuracy_and_precision
2006-09-08 22:40:33 · answer #4 · answered by bellerophon 6 · 0⤊ 0⤋