Keywords

Independent Variable

• The Variable for which the values are selected by the investigator. (the one you changed)

Dependent Variable

• The variable for which the values change when the independent variable is changed. (the one you measured)

Controlled Variable

• A variable which may affect the outcome of the investigation and therefore should be kept constant.

Range

• The maximum and minimum values of the independent or dependent values. This should not be too big or too small.

Valid Conclusion

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

Validity of Experimental Design

• Suitability of the investigation procedure to answer the question being asked. Strategies to ensure validity include fair tests and controls that aim to isolate the effect of the independent variable on the dependent variable.

Anomaly

• Value in a set of results which is judged not to be part if the inherent variation.

Resolution

• This is the smallest change in the quantity being measured by a measuring instrument that can be observed. For example ± 1mm on a meter ruler.

Anomaly

• Value in a set of results which is judged not to be part of the inherent variation.

True Value

• This is the value that would be obtained in an ideal experiment

Uncertainty

• The interval within which the true value can be expected to lie, e.g: the temperature is 20°C ± 2°C

Measurement error

• The difference between a measured value and the true value

Systematic error

• These cause readings to differ from the true value by a consistent amount each time a measurement is made. Systematic errors can include the influence of the environment, the methods of observation or the instruments used. The effect of systematic errors cannot be reduced by increased repeats

Random error

• These occur due to results varying in an unpredictable way from one measurement to the next. The effect of random errors can be reduced by taking more measurements and calculating a mean

Accuracy

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

Precision

• This shows the closeness of agreement between values. It gives no indication of how close results are to the true value

Repeatability

• The precision obtained when repeat readings are obtained by a single learner/group

Repeatable

• A measurement is repeatable, if repetition by a single learner/group using same method and equipment, obtains the same or similar results

Reproducibility

• The precision obtained when repeat readings are obtained by a different learners/groups

Reproducible

• A measurement is reproducible, if repetition by different learners/groups obtains the same or similar results. This could include using different equipment/ methods. This is a harder test of the quality of data

Hazard

• A chemical or piece of apparatus that could cause harm. It is expected that in risk assessments the nature of the hazard is also specified

Risk

• An action involving a hazard that might results in danger

Control measure

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