Precision versus accuracy

4 minAS Level1.3.11.3.2

AI-drafted, independently checked · not yet teacher-reviewed

By the end of this lesson

By the end you can state precisely what accuracy and precision mean, tell them apart in a set of readings, and link each one to the type of error that spoils it.

Definition

Accuracy

How close a measured value (or the mean of repeated measurements) is to the true value.

Definition

Precision

How close repeated measurements of the same quantity are to each other: a small spread means high precision.

Precision is about the spread of the dots. Accuracy is about where their mean sits compared with the true value.

Quick check

DefinitionQuestion 1 · Recall

Define precision as applied to a set of measurements.

Multiple choiceQuestion 2 · Recall

A student measures the acceleration of free fall five times and gets 9.52, 9.53, 9.51, 9.52 and 9.53 m s⁻². The accepted value is 9.81 m s⁻². How would you describe the results?

Aprecise but not accurateBaccurate but not preciseCboth accurate and preciseDneither accurate nor precise

Answer the 2 questions above to continue.

Previous lessonSystematic errors, random errors and zero errors Next lessonUncertainty in sums and differences