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4 Scatter Diagrams
Scatter diagrams are a type of representation of data that uses scatter points to
identify trends. An example can be seen in the figure shown below. A positive
correlation means that as x increases, y also increases. Zero correlation means
the x and y variables are not related at all - there’s no relationship/trend be tween
them. A negative correlation means an inverse relation as one increases,
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the other decreases. For example, it can be that as y increases, x decreases or
vice versa.
You should also know how to make a best fit line. A best fit line is a line that
represents the approximate correlation between the two variables graphi cally -
this line should pass through the middle of the entire dataset and should have
roughly equal number of points above and below it to ensure it’s an accu rate
representation of the correlation. A best way to draw this is to use your ruler and
roughly draw a number of lines and see which one best fits how the data
progresses as you move forward on the x-axis, for example. The line of best
should follow the following rules:
1. It should be a single ruled line drawn by inspection
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