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TWO-VARIABLE LINEAR REGRESSION
The population regression model is: y = β1 + β2 x + u
We wish to estimate the regression line: y = b1 + b2 x
REGRESSION USING THE DATA ANALYSIS ADD-IN
This requires the Data Analysis Add-in: see Excel 2007 and 2003: Access and Activating the Data Analysis Add-in
The data used are in carsdata.xls
- In the Data Group select the Data Analysis Add-in
- Select Regression Analysis
We select OK and fill out the dialog box as follows
We obtain
INTERPRETING THE REGRESSION SUMMARY OUTPUT
The key output is given in the Coefficients column in the last set of output:
- b1 = 0.8 (the Intercept coefficient)
- b2 = 0.4 (the Coefficient of HH SIZE : the slope coefficient)
or CARS = 0.8 + 0.4 HHSIZE
The regression statistics outyput gives measures of how well the model fits the data. In particular
- R2 = 0.8 which measures the fit of the model
This means that 80% of the variation of yi around ybar is explained by the regressor xi - Standard error = 0.365 which measures the standard deviation of yi around its fitted value.
The remaining output (ANOVA table and t Stat, p-value, .... ) is used for statistical inference.