Resolution is more like sensitivity, it is the smallest possible change of the parameter that can be detected.
Accuracy on the other hand is a deviation between the measured and the "true" value. In other words the accuracy can be described as a maximum operating error that can be expected under worst case conditions.
These conditions include noise, time and temperature drifts, offset and gain errors etc.
The accuracy and the resolution are not the same, though can be measured in the same units. For example, a 10 bit A/D converter has a resolution of 1/1024, while the accuracy of the results can be 20 times worse.
The pictures below represent measurements on the target. On the third picture the accuracy is limited by the resolution of the instrument.
The first picture illustrates the case when we need a good resolution but less care about the accuracy.
For example, it could be a system with a regulation unit, and you want to make fine adjustments on the regulation unit by very small steps.
Question from N.S:
The accuracy of my power source is specified like this:
Range = 400uA
Resolution = 12nA
Accuracy = +/-(100nA+0.2%)
What is 0.2%?
Answer:
Well, 100nA - must be the DC offset of your instrument. On top of that you have 0.2% of your range.
Which is 0.8uA. So the worst case will be: 0.8uA+100nA=0.9uA
Question from Napoel:
What about other terms like Fidelity, Precision? Are they synonyms?
Answer:
Fidelity is a synonym to Accuracy.
Precision quantifies the distribution of a group of repeated measurements. You can think of
precision as (Resolution x Repeatability).
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