Chapter 14 Notes:
Inference for the Regression Model:


Step 1: Make a scatterplot


Step 2: Calculate the LSRL

Step 3: Identify outliers and influential points


Step 4: Calculate the correlation (r value)




Assumptions for Regression Inference:

1. The y responses vary according to a normal distribution.

2. The y responses are independent of each other.

3. The true relationship is linear.

4. The standard deviation s about the true regression line is constant.




The true regression line is written in the form: where a is the true x-intercept and b is the true slope.


Since s is unknown, we use s to estimate the value of s.


Note: (n 2) is the degrees of freedom for the regression model.




A level C confidence interval for the slope b of the true regression line is .




To test whether or not there is a correlation between two quantitative variables, consider the slope of the regression line. If there is no correlation, the slope would be zero.

H0: b = 0


To test this hypothesis, compute the t statistic and P-value.