ABSTRACT
For many investigations it will be enough to know the extent of correlation between two variables; in these situations the calculation of r, or some variant of it, is sufficient. There are, however, occasions when we wish to make a prediction about the value of one variable given that some particular value of the other variable has been obtained. For example, using the data from Figure 5.1, what level of achievement is to be predicted for a child whose aptitude test score is 60? In this section we shall see how the correlation coefficient is involved in making such predictions.
