16. Now, check the Correlation coefficient box in the applet to reveal the actual value of the correlation coefficient. Report the value. Key Idea The correlation coefficient is only applicable for data which has a linear form; nonlinear data are not summarized well by the correlation coefficient. In fact, we could say that the correlation coefficient is a numerical summary of the strength and direction of a linear association between two quantitative variables. Another point about correlation is that it is sensitive to influential observations. Influential observations are unusual observations which substantially impact the value of the correlation coefficient based on whether or not they are included in the dataset