Difference between revisions of "Precise"

Revision as of 14:41, 3 April 2019

Results are precise if the same reading or measurement repeatedly gives a similar value.

The smaller the range and uncertainty the greater the precision.

Precision is achieved by controlling variables so that readings are stable over a long period of time.

A single reading may be more precise if the resolution of the measuring instrument is higher. This is due to the upper and lower bounds of a single number being smaller when the number has a greater resolution. A ruler that measures to the nearest 1cm has an uncertainty of ±5mm for each reading. A ruler that measures to the nearest 1mm has an uncertainty of ±0.5mm, making a single reading more precise.

Experimental Measurements of pi
Method	Test 1	Test 2	Test 3	Average	Range
Method 1	3.27	3.09	3.01	3.12	0.26
Method 2	3.91	3.88	3.88	3.89	0.03
Method 3	3.57	2.89	2.93	3.13	0.68
The number pi is 3.14159265359 correct to 12 significant figures. Method 1: The most accurate measurements because they are the closest to pi but they are not very precise because they have a range of 0.26. Method 2: These are the least accurate measurements because they are the furthest from pi but they are very precise because they have a range of only 0.03. Method 3: Each measurement is not accurate because they are far from pi, they are also the least precise because they have a range of 0.68. However, the average is the most accurate as it is the closes to pi.

@@ Line 6: / Line 6: @@
 : The smaller the [[range]] and [[uncertainty]] the greater the '''precision'''.
 : '''Precision''' is achieved by [[Control Variable|controlling]] [[variable]]s so that [[reading]]s are stable over a long period of [[time]].
-: A single [[reading]] may be more [[precise]] if the [[resolution]] of the [[Measuring Instrument|measuring instrument]] is higher. This is due to the [[Upper Bound|upper]] and [[Lower Bound|lower bounds]] of a single number being smaller when the number has a greater [[resolution]]. A [[ruler]] that [[measure]]s to the nearest 1cm has an [[uncertainty]] of ±5mm for each [[reading]]. A [[ruler]] that [[measure]]s to the nearest 1mm has an [[uncertainty]] of ±0.5mm, making a single [[reading]] more [[precise]].
+: A single [[reading]] may be more [[precise]] if the [[resolution]] of the [[Measuring Instrument|measuring instrument]] is higher. This is due to the upper and lower bounds of a single number being smaller when the number has a greater [[resolution]]. A [[ruler]] that [[measure]]s to the nearest 1cm has an [[uncertainty]] of ±5mm for each [[reading]]. A [[ruler]] that [[measure]]s to the nearest 1mm has an [[uncertainty]] of ±0.5mm, making a single [[reading]] more [[precise]].
 ===Accuracy vs Precision===