Mathematics Throughout History

Development Ofweights and Measures

What is accuracy in measurement?

Accuracy in measurement is based on relative error and number of significant digits. Relative error is the absolute error divided by the calculated (or estimated) value. For example, if a person expects to spend $10 per week at the local espresso bar, but actually spends $12.50, the absolute error is 12.50 - 10.00 = 2.50; the relative error then becomes (2.50 / 10) = 0.25 (to find out the percent, multiply by 100, or 0.25 × 100 = 25 percent of the original estimate). Significant digits refers to a certain decimal place that determines the amount of rounding off to take place in the measurement; these numbers carry meaning to the figure’s precision. But beware—accuracy in measurement does not mean the actual measurement taken was accurate. It only means that if there are a large number of significant digits, or if the relative error is low, the measurement is more accurate.


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