What is the relation between the standard deviation and the precision of a procedure? What is the relation between standard deviation and accuracy?
2006-09-23 07:55:26 · 4 answers · asked by Timothy A 1 in Science & Mathematics ➔ Chemistry
Hi. Precision is how tightly the procedure is controlled. Accuracy is how close it is to nominal. An archer that hits a target in a tight pattern is precise but she could miss the bulls-eye 100% of the time. Another archer could have a group centered on the bulls-eye but with a greater spread. Not precise but more accurate. This concept can apply to any process. These both tie into Cp and Cpk. Cp is the tight pattern.
2006-09-23 07:57:22 · answer #1 · answered by Cirric 7 · 0⤊ 0⤋
Standard deviation is a measure of how widely the results of experiment (or observations) are spread.
For a mound shaped distribution usually most about 95% of the data points are within 2 std dev units of the mean.
Precision is a general term regarding the spread of a distribution, things with a high precision have a low standard deviation, but this says nothing of the accuracy of the measurements.
Accuracy means that on average the data points are true, but that does not exclude the possibility of widely variation in the measurements.
To quote, "precision of measurements has to do with getting essentially the same values every time a particular measurement is done". Statistical Quality Assurance Methods for Engineers by Stephen B. Vardeman, and J.Marcus Jobe, page
17.
2006-09-23 09:23:37 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Standard deviation can be said to be the root-mean-square error of a data set with respect to its mean.
Precision and accuracy can be said to have an inverse relationship to standard deviation.
Precision is sometimes used to mean the difference between a result and a desired outcome. In this case the difference between the mean of the outcomes and the desired result expressed as x standard deviations. Again, the smaller x is, the better the precision is.
2006-09-23 08:15:50 · answer #3 · answered by Helmut 7 · 0⤊ 0⤋
the line of deviation should be more fine and smooth with precision more than accuracy ,, the percentage error in accuracy will be higher than precision
2006-09-23 09:36:34 · answer #4 · answered by source_of_love_69 3 · 0⤊ 0⤋