PHYSICS 102 Lecture Notes - Lecture 3: Standard Deviation, Multimodal Distribution, Random Effects Model
Document Summary
If the true value is known, then the accuracy of the measurement may be assessed. If no uncertainty is quoted, then the assumption is that the last figure in the measurement is the best that can be determined and so the uncertainty is a half of this: If x = 5. 6 then x = 0. 05: write as 5. 60 +/- 0. 05 (e. g. between 5. 55 and 5. 65) If x = 5. 603 then x = 0. 0005; write as 5. 6030 +/- 0. 0005 (e. g. between 5. 6025 and 5. 6035) Random uncertainty: produces a scatter of values due to random effects such as poor resolution, electrical noise, human failings; for single measurement it must be estimated; for repeat measurements it may be calculated. Systematic uncertainty: arises through incorrect calibration or mistake in experimental design often resulting in an off-set value (bias); once identified it is often possible to correct for such an error.
