Download Presentation
## Correlation

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**Correlation Coefficient (r)**Quantitative assessment of the strength of the relationship between x & y. It is the measure of the extent to which x & y are linearly related. *It is strong if the points lie close to a straight lint and is weak if they are widely scattered about a line.**Correlation (r)**• It’s a number between -1 and 1. • The closer it is to the ends, the stronger the positive or negative relationship. • It gives the strength and direction. Strong Negative No Correlation Strong Positive -1 1 0**Let’s explore….**• www.whfreeman.com/tps4e**Pearson’s Correlation Coefficient**Think about z-scores of the x & y**Pearson’s Correlation Coefficient**Think about z-scores of the x & y**Pearson’s Correlation Coefficient**Think about z-scores of the x & y**AP Exam Tip**If you are asked to interpret a correlation start by looking at a scatterplot of the data. Then be sure to address direction, form, strength, and outliers and put your answer in context.**Properties of “r”**• It does not depend on the unit of measurement. • It doesn’t depend upon which of the 2 variables is “x” • It’s between -1 and 1 • It equals -1 or 1 if all points lie on a straight line • It is strongly affected by a few outliers**Try One!**• Create scatterplot • Find the correlation • Describe the association**Homework**• Page 160 (14-18, 21, 26)