3.8 Precision & Accuracy
We can determine the accuracy of a measurement instrument by comparing the experimental mean of a large number of measurements of a sample for which we know the "true value" of the characteristic of the sample. A sample for which we know the "true value" would be our calibration standard. We may also need to characterize the accuracy of the measurement instrument by observing historical trends in the distribution of measured values for the calibration standard (this allows for determining the systematic error expected from environmental effects, etc.). The effects of systematic uncertainties cannot be reduced by repeated measurements. The cause of systematic errors may be known or unknown. If both the cause and the value of a systematic error are known, it can be corrected for by "subtracting" the known deviation. However, there will still remain a systematic uncertainty component associated with this correction.
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Conclusion:
1. Why is it important to know the accuracy and precision of a measuring device? Answer: It's important to know the accuracy & precision of a measuring device because, this knowledge can tell you how accurate/precise your tool is & the measurement you get from it. 2. Do you think that the dial caliper manufacturer’s claim that the accuracy of the instrument is ±.001 is appropriate? Why or why not? Answer: I think if you disregard user error, this claim could be very accurate because the dial caliper does calculate to the .001th of an inch. 3. Do you think that either of the dial calipers needs to be adjusted in order to accurately display measurements? Answer: Yes, if you just go & try to use the dial caliper as it is, without recalibrating, it you are bound to have many errors. |