ABSTRACT
SSYY (MATHS)=60.4 and SSXX (SMATHS)=1030.4. (These correspond with the values calculated in the previous regression example). Using the general formula for calculating sums of squares, for the two variables MATHS and RAVEN,
The correlation between MATHS (M) and SMATHS (SM) is therefore
and the correlation between MATHS (M) and
RAVEN (R) is
Interpretation
The plot of MATHS*SMATHS suggests an approximate linear trend but the plot of MATHS*RAVEN appears to be non-linear as far as it is possible to tell with as small a sample as this. This later plot also has a very obvious outlier observation. If this pattern (for MATHS vs RAVEN) had been obtained with a larger sample, it would provide good evidence for not using a Pearson correlation statistic. It is noticeable that one variable, RAVEN has a smaller range and less variability in the scores than the other variable (SMATHS).
