accuracy vs precision

Question

Repeated measurements of a length give 12.36, 12.37, 12.36, 12.37 cm while true value is 12.50 cm. This set is?

RankGuru · Accepted Answer

1. **Precision**: Refers to the closeness of two or more measurements to each other (resolution and consistency). Since the values ($12.36, 12.37, \dots$) differ by only $0.01$ cm, the set is highly **precise**.
2. **Accuracy**: Refers to the closeness of a measured value to a standard or known (true) value. 
3. **Analysis**: The mean of the measurements is $\approx 12.365$ cm. The true value is $12.50$ cm. The deviation ($0.135$ cm) is significant relative to the resolution.
4. **Conclusion**: The measurements are consistent with each other (Precise) but far from the truth (**Not Accurate**). This often indicates a systematic error.

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accuracy vs precision

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