HOW SCIENCE WORKS GLOSSARY
Fair Test When only one variable (the independent variable) is changed and all others are controlled
Independent Variable The variable that is changed by the investigator
Dependent Variable The variable that is measured
Control Variable A type of variable that must be kept constant and not changed in a fair test
Categoric Variable A variable that can generally only be described by a word, such as a chemical name (e.g. carbon dioxide, oxygen or nitrogen)
Ordered Variable A variable that can be put into sequence but not assigned a value, e.g. observed size of elephants
Discrete Variable A variable that is described by a whole number, e.g. number of bubbles evolved
Continuous Variable A variable that is measured to give a value that could be any number, e.g. the volume of gas evolved in cm3
Causal Link When one variable has directly caused a change
in the other
Association One variable could be changed by another but it may also be changed by a third variable
Chance One variable does not cause another to change even if there is a correlation between the two
Reliable If an experiment can be repeated by another person and the same results are obtained
Precise If repeated measurements are very close together
Accurate If measured values are close to the true value
Valid If experimental results definitely answer the question the experiment was designed to answer
Systematic Error An error caused repeatedly by a flaw in the
procedure
Random Error An error caused due to inconsistent or poor
measurement
Anomaly A result that is clearly out of line with the other results. Could be discarded unless it can be explained
Range The spread of the data obtained. If the smallest value recorded was 2cm and the largest was 17cm, it would be 2-17cm
