Defining and Visualizing Correlation

Defining and Visualizing Correlation

A correlation is defined as a measure of the extent to which to variables are linearly related. However, before we learn more about correlations, we need to examine a way to display the relation between two variables x and y. The most common and easiest way is a scatter plot. The following example illustrates a scatter plot.

A scatter plot shows the direction of a relationship between the variables. Generally, the direction of the relationship can be either positive or negative. The direction of the relationship is positive if as one variable increases, the other variable increases as well, or if one variable decreases, the other variable decreases as well. The direction of the relationship is negative if as one variable increases, the other variable decreases. If as one variable increases or decreases, there is no change in the other variable, we say that these variables have no relationship.

You can determine the strength of the linear correlation by looking at the scatter plot and seeing how close the points are to a line. The closer the points fall to a straight line, the stronger the relationship.

When you look at a scatterplot, you want to notice both the direction and the strength of the relationship. Use the arrows below to scroll through some examples.

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