Regression Analysis

• Purpose: to determine the regression equation; it is used to predict the value of the dependent variable (Y) based on the independent variable (X). 
• Procedure: select a sample from the population and list the paired data for each observation; draw a scatter diagram to give a visual portrayal of the relationship; determine the regression equation.
• The regression line 
• A straight line that represents the relationship between two variables 
• Useful to add to the scatterplot to help us see the direction of the relationship 
• But it’s much more than this… 
• Prediction 
• Regression line enables us to predict Variable Y on the basis of Variable X

• b 
• The slope of the regression line 
• The amount of change in Y associated with a one-unit change in X
•  a 
• The intercept 
• The point where the regression line crosses the Y axis 
• The predicted value of Y when X = 0