As is our usual strategy, we turned from graphs to numeric measures, and in particular, we developed the correlation coefficient, r, as a measure of the strength of the linear relationship we observed...As is our usual strategy, we turned from graphs to numeric measures, and in particular, we developed the correlation coefficient, r, as a measure of the strength of the linear relationship we observed in the graph. Finally, we used the equation of the regression line to predict the value of the response variable for a given value of the explanatory variable. In other words, we can think of the error as the amount that we have to add to the prediction to get the observed value.
