Key practical terms

Question 1

What is accuracy?

Answer 1

The closeness of agreement between the test value and the true value

Question 2

What is confidence?

Answer 2

The extent to which a conclusion is justified by the evidence

Question 3

What is error of measurement?

Answer 3

The difference between an individual measurement and the true value

Question 4

What is precision?

Answer 4

The closeness of agreement between independent measurements under the same conditions (not to do with the true value)

Question 5

What is repeatability?

Answer 5

The precision of results using the same equipment in the same place (i.e an experiment is repeatable if can do the experiment many times and get the same results)

Question 6

What is reproducibility?

Answer 6

The precision of results using different (but equivalent) equipment in a different place (i.e an experiment is reproducible if someone else can follow exactly what you did in another lab and get the same results)

Question 7

What is uncertainty?

Answer 7

An estimate attached to a measurement that indicates the possible range of values (e.g. 45cm +/-0.5cm)

Question 8

What is a systematic error?

Answer 8

Where there is a flaw in the design of the experiment or in a piece of equipment that makes the same mistake every time

Question 9

What is a random error?

Answer 9

An error that is different every time, caused by human error or by the uncertainty with a piece of equipment