Science practical key terms

Hazard

A chemical or piece of apparatus that could cause harm.

Risk

An action that could result in the hazard causing harm – the dangerous part of the method.

Control measures

Something that can be done to reduce or prevent a risk while allowing you to carry out the experiment.

Variable

The variable that you change.

Dependent variable

The variable that you measure and record during the investigation – the results.

Controlled variable

A variable that should be kept the same because it may affect the investigation.

Range

The maximum and minimum values of the independent or dependent variables.

Accuracy

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

Anomaly/Anomalous

Value in a set of results which does not fit with the other results.

Reliability

For the data to be reliable, the repeat results must be close together.

Repeatable

Results are repeatable if the experiment is carried out by a single student/group and the repeat results are close together.

Reproducible

Results are reproducible, if repeats by different students/groups obtain the same or similar results.

Resolution

The smallest change in the quantity being measured by a measuring instrument that can be observed.

Valid conclusion

A conclusion supported by valid data, obtained from an appropriate experimental design and based on sound reasoning.

Validity of experimental design

Suitability of the investigative procedure to answer the question being asked.

Measurement error

The difference between a measured value and the true value.

Precision

Shows the closeness of agreement between measured values.

Random error

Errors due to results varying in an unpredictable way from one measurement to the next.

Systematic error

Errors that cause readings to differ from the true value by a consistent amount.

True value

The value that would be obtained in an ideal measurement.

Uncertainty

The interval within which the true value can be expected to lie, with a given level of confidence.