Scientific Key Words

Question 1

Accuracy

Answer 1

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

Question 2

Anomalies

Answer 2

Therese are values in a set of results which are judged no to be part of the variation caused by random uncertainty

Question 3

Uncertainty

Answer 3

The interval within which the true value can be expected to lie, with a given level of
confidence or probability, eg ‘the temperature is 20 °C ± 2 °C, at a level of confidence of 95%’.

Question 4

Resolution

Answer 4

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

Question 5

Repeatability

Answer 5

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 6

Reproducibility

Answer 6

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 7

Precision

Answer 7

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 8

Validity

Answer 8

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.

Question 9

Atmospheric pressure

Answer 9

Atmospheric pressure is the pressure exerted by the earth’s atmosphere at any given point, being the product of the mass of the atmospheric column of the unit area above the given point and of the gravitational acceleration at the given point.

Question 10

Random error

Answer 10

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

Question 11

Systematic error

Answer 11

An error that causes readings to differ from the true value by a consistent amount each time a measurement is made.