Precision, Accuracy and Errors

Answers to Practice Worksheet 3.1

Practice Worksheet 3.1 - Precision, Accuracy and Errors

Question 1:

• Bob is reasonably accurate but not very precise at all.  Bob’s final result was lucky.  His experimental skills are inconsistent with random errors.
• Jiwan is not that accurate or precise either.
• Sue is very precise but not accurate.  Her experimental technique is consistent but has a systematic error.
• Charles is both precise and accurate.

  These comparisons are QUALITATIVE rather than QUANTITATIVE.

Question 2:

An impure sample would have given a systematic error. The experiment, if carefully done, would have given a precise, yet inaccurate result. It is likely that Sue had an impure sample.

Question 3:

Bob:                0.702 % error
Jiwan:              12.8 % error
Sue:                 8.15 % error
Charles:          0.281% error

Using % error values to compare an experimental value to an actual value is much more meaningful than saying “our results are close”

 

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