Welcome to this deck on scatter graphs. Scatter graphs are a great way to see if there's a connection between two different sets of information. For example, is there a link between the temperature outside and how many ice creams a shop sells? By the end of this deck, you'll understand how to plot these graphs, describe the relationships you see, and use them to make predictions.

Scatter graphs are used to display 'bivariate data'. The 'bi' part of the word means two, and 'variate' relates to variables. So, bivariate data is simply data that has two variables. For example, if we collected the height and the weight of a group of people, that would be bivariate data.

To plot a scatter graph, you take each pair of data values and plot them as a coordinate on a graph. One variable goes on the horizontal x-axis, and the other goes on the vertical y-axis. Each pair of values becomes a single point, usually marked with a cross.

The whole point of a scatter graph is to look for a relationship, which in maths we call 'correlation'. When you look at the pattern of the points, you can see if the two variables affect each other. There are three main types of correlation we look for.