What type of linear correlation might exist if the slope of the line of best fit equals zero?
Let’s begin by considering what this might look like on a scatter diagram. If the slope of our line of best fit equals zero, we know that the line is horizontal. We might be tempted to think that our correlation here is strong, as all the points are close to the line. However, looking at the graph more closely, it is clear that knowing the value of one of the variables tells us nothing about the value of the other. If we let the value of 𝑦 where the line of best fit intersects the 𝑦-axis be five, this represents the whole range of 𝑥-values. Knowing that the value of 𝑦 is five does not enable us to predict the value of 𝑥. We can therefore conclude that when the slope of the line of best fit equals zero, there is no correlation.