Definition:Accuracy

Definition

Accuracy is a measure of how closely a reported number matches the true value of that number.

Significant Figures

A representation $y$ in decimal notation of a number $x$ is accurate to $n$ significant figures if and only if the first $n$ digits of $x$ match, after rounding, the first $n$ digits of $y$.

In this context it is usual for $y$ to be expressed only by $n$ digits.

Decimal Places

A representation $y$ in decimal notation of a number $x$ is:

accurate to $n$ decimal places

if and only if:

the number $n$ of digits after the decimal point of $x$ match the first $n$ digits after the decimal point of $y$, without rounding.

Also known as

In the same way one can refer to a value as being accurate to $n$ decimal places or to $n$ significant figures, one can also say correct to $n$ decimal places or $n$ significant figures.

Also see

• Definition:Error
• Definition:Precision

• Results about accuracy can be found here.

Sources

• 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): accuracy