What is uncertainty of measurement?
Uncertainty of measurement is the doubt that exists about the result of any measurement.
Expressing uncertainty of measurement Since there is always a margin of doubt about any measurement, we need to ask ‘How big is the margin?’ and ‘How bad is the doubt?’ Thus, two numbers are really needed in order to quantify Measurement Good Practice Guide No. 11 (Issue 2) 2 an uncertainty. One is the width of the margin, or interval. The other is a confidence level, and states how sure we are that the ‘true value’ is within that margin. For example: We might say that the length of a certain stick measures 20 centimetres plus or minus 1 centimetre, at the 95 percent confidence level. This result could be written: 20 cm ±1 cm, at a level of confidence of 95%.
Uncertainty of measurement is the doubt that exists about the result of any measurement.
Expressing uncertainty of measurement Since there is always a margin of doubt about any measurement, we need to ask ‘How big is the margin?’ and ‘How bad is the doubt?’ Thus, two numbers are really needed in order to quantify Measurement Good Practice Guide No. 11 (Issue 2) 2 an uncertainty. One is the width of the margin, or interval. The other is a confidence level, and states how sure we are that the ‘true value’ is within that margin. For example: We might say that the length of a certain stick measures 20 centimetres plus or minus 1 centimetre, at the 95 percent confidence level. This result could be written: 20 cm ±1 cm, at a level of confidence of 95%.
