Practical terms

Question 1

Accuracy

Answer 1

a measure of the closeness of agreement between an individual test result and the true value. Close to the true value = accurate.

Question 2

Anomaly

Answer 2

outlier; a value in a set of results that is judged not to be part of the inherent variation.

Question 3

Confidence

Answer 3

a qualitative judgement expressing the extent to which a conclusion is justified by the quality of the evidence.

Question 4

Precision

Answer 4

the closeness of agreement between independent measurements obtained under the same conditions. Depends only on spread of measurements, not the true value.

Question 5

Repeatability

Answer 5

the precision obtained when measurement results are produced over a short timescale by one person or the same group using the same equipment in the same place.

Question 6

Reproducibility

Answer 6

the precision obtained when measurement results are produced over a wider timescale by different people using equivalent equipment in equivalent places.

Question 7

Resolution

Answer 7

the smallest change in the quantity being measured that can be detected by an instrument.

Question 8

Uncertainty

Answer 8

an estimate attached to a measurement which characterises the range of values within which the true value is asserted to lie.

Question 9

Validity

Answer 9

can be applied to an individual experiment or the whole investigation
• Measurement = valid if it measures what is supposedly being measured
• Investigation = valid if it is suitable to answer the question being asked

Question 10

How to improve accuracy

Answer 10

Repeat

Question 11

How to improve precision

Answer 11

Improve measuring instruments (within reason)