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.