Linear Correlations

Linear Correlations: measure the strength of association between 2 variables

Variables are X and Y but they are different from regression analysis

-no independent or dependent variables - just 2 different variables

3 types of relationships

• positive
• negative
• none

Use the correlation coeficient to measure the strength of association

-referred to as the simple correlation coefficient, PPM or Pearson product Moment correlation coefficient

Coefficent of determination, r² - square of the correlation coefficient, amount of variation in one variable explained by the correlation of both variables.

Assumptions for statistical testing:

-X values at each Y are assumed to have been randomly drawn from a normal population of X values
-Y values at each X are assumed to have been randomly drawn from a normal population of Y values

Steps:

1. statistical hypotheses
2. calculate the correlation coefficient
3. conduct statistical tests 

-use the cricital values of the correlation coefficient
-t testing
-F testing