Subject specific vocabulary

Question 1

Measurement error

Answer 1

The difference between a measured value and a true value

Question 2

Anomalies

Answer 2

These are values in a set of results which are judged not to be part of the variation caused by random uncertainty

Question 3

Define random error

Answer 3

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

Question 4

When are random errors present and how can the effect of random errors be reduced?

Answer 4

• present when any measurement is made and cannot be corrected
• the effect of random errors can be reduced by making more measurements and calculating a new mean

Question 5

Define systematic error

Answer 5

These cause readings to differ from the true value by a consistent amount each time a measurement is made

Question 6

What are the sources of systematic error?

Answer 6

Can include the environment, methods of observation or instruments used

Question 7

What should you do if a systematic error is suspected?

Answer 7

• systematic errors cannot be dealt with by simple repeats
• if a systematic error is suspected, the data collection should be repeated using a different technique or a different set of equipment and the results compared

Question 8

Define zero error

Answer 8

Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero

Question 9

What’s an example of zero error?

Answer 9

e.g. the needle on an ammeter failing to return to zero when no current flows
A zero error may result in a systematic uncertainty