How Science Works Precision How small a measurement is. Millimetres are more precise than centimetres because they are smaller.

How Science Works Accuracy How close a measurement is to its true value.

How Science Works Random errors Errors caused by factors we can’t control, like tiny temperature changes in a room. They can also happen if you make a mistake – like pushing the stopwatch button too early.

How Science Works Systematic errors Errors caused by inaccurate equipment, equipment that doesn’t zero properly or by problems with a method.

How Science Works Reliability If someone else can repeat your measurements and get the same results then your results are reliable. Carrying out repeat measurements checks the reliability of your results.

How Science Works Independent variable The variable you change to see what happens.

How Science Works Dependent variable The variable that you measure.

How Science Works A fair test An investigation or experiment where only the independent variable has been allowed to affect the dependent variable. This means only changing one variable and keeping everything else the same.

How Science Works Validity Your results must be valid if you are going to be able to draw a conclusion from them. To get valid results you need to carry out a fair test.

How Science Works Continuous variables Variables that can have any numerical value. You should use a line graph to show this type of data.

How Science Works Categoric variables Variables that are described by labels. You should use a bar chart to show this type of data.