Keywords

Question 1

Accuracy

Answer 1

A measured value that is close to the true value.

Question 2

Random error

Answer 2

These cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next.

Question 3

Precision

Answer 3

Precise measurements are ones in which there is very little spread about the mean value. Precision depends only on the extent of random errors – it gives no indication of how close results are to the true value.

Question 4

Systematic errors

Answer 4

These cause readings to differ from the true value by a consistent amount each time a measurement is made.
Sources of systematic error can include the environment, methods of observation or instruments used.

Question 5

Repeatability

Answer 5

A measurement is repeatable if the original experimenter repeats the investigation using same method and equipment and obtains the same results.

Question 6

Reproducibility

Answer 6

A measurement is reproducible if the investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained.

Question 7

Uncertainty

Answer 7

The interval within which the true value can be expected to lie, with a given level of confidence or probability.

Question 8

Resolution

Answer 8

This is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.