Science Keywords

Question 1

Accuracy:

Answer 1

A measurement result is considered accurate if it is judged to be close to the true value.

Question 2

Calibration

Answer 2

Marking a scale on a measuring instrument. This involves establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied. For example, placing a thermometer in melting ice to see whether it reads zero, in order to check if it has been calibrated correctly.

Question 3

Data:

Answer 3

Information, either qualitative or quantitative, that has been collected.

Question 4

Error:

Answer 4

See also uncertainty.

Question 5

Measurement error:

Answer 5

The difference between a measured value and the true value.

Question 6

Anomalies:

Answer 6

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

Question 7

Random Error:

Answer 7

These cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next. Random errors are 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 8

Systematic error

Systematic error:

Answer 8

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. 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 9

Zero Error:

Answer 9

Any indication that a measuring system gives a false reading when the true value of a
measured quantity is zero, eg the needle on an ammeter failing to return to zero when no
current flows. A zero error may result in a systematic uncertainty.

Question 10

Evidence

Answer 10

Data which has been shown to be valid.

Question 11

Fair test

Answer 11

A fair test is one in which only the independent variable has been allowed to affect the
dependent variable.

Question 12

Hypothesis

Answer 12

A proposal intended to explain certain facts or observations.

Question 13

Interval

Answer 13

The quantity between readings, eg a set of 11 readings equally spaced over a distance of 1
metre would give an interval of 10 centimetres.

Question 14

Uncertainty

Answer 14

confidence or probability, eg ‘the temperature is 20 °C ± 2 °C, at a level of confidence of 95%’.

Question 15

Resolution

Answer 15

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

Question 16

Accuracy

Answer 16

A measurement result is considered accurate if it is judged to be close to the true value.

Question 17

Repeatability

Answer 17

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

Question 18

Reproducibility

Answer 18

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. Previously known as
reliable.

Question 19

Precision

Answer 19

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 20

Validity

Answer 20

Suitability of the investigative procedure to answer the question being asked. For example, an
investigation to find out if the rate of a chemical reaction depended upon the concentration of
one of the reactants would not be a valid procedure if the temperature of the reactants was
not controlled.