1. Correlation

2. Correlation is a measure of the strength of the relation between two or more variables. Any correlation coefficient has two parts – Valence: it shows the direction of correlation – Value: it shows the strength of the relation

3. Scatter Diagram To see what is a correlation, lets’ draw the scatter diagram of the first example To draw the scatter diagram, we need to put one variable on x axis and the other on y axis.

4. Scatter Diagram There could be different kinds of correlations: – Negative correlation – Positive correlation – Curvilinear Correlation – Zero Correlation

5. Calculation To calculate Pearson’s correlation coefficient, we need to validate some assumptions – Normal Distribution – Linearity – Independency of measurements – Scaling

6. Calculation Validating the basic assumptions we can compute r by finding – Deviation scores – Squared deviation scores – Cross-products of deviation scores