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Studying the data

Data collected during an investigation is normally displayed in a results table. At this point you can study your repeats to see how close they are. Repeats that are similar are said to be precise. Sometimes you may have an anomalous repeat. If this is the result of a measurement error it can be ignored, although it is good practice to repeat that measurement again.

How to display the data

It can be difficult to see the relationship between the variables from a results table so often the means are plotted on a graph or chart to analyse the results further. It is important to choose the most appropriate type of graph or chart.

If both the independent and dependent variables are continuous data then a line graph (also called a scatter graph) is the best choice. Usually a line of best fit will be drawn to show the trend in the data. This will allow you to see the relationship between the variables, for example if they are proportional.

Also, you can see if any of the values are anomalous as they will be placed far away from the line of best fit. An example of where a line graph would be used is in an investigation to see if temperature affects the rate of a reaction.

A bar chart is used if the independent variable has different categories. For example, to display the frequency of different eye colours in a group of people.