Simple Linear Regression. Least squares line Interpreting coefficients Prediction Cautions The formal model. Section 2.6, 9.1, 9.2. Professor Kari Lock Morgan Duke University. Exam 2 Grades. In Class:. Lab:. Total:. Comments on In-Class Exam.
Response Variable, y
We will fit a model to predict temperature based on cricket chirp rate
Want to make all the residuals as small as possible.
How would you measure this?
chirps per min
chirps per minute
Which of the following interpretations is correct?
A decrease of 0.89 in the birth rate corresponds to a 1 year increase in predicted life expectancy
Increasing life expectancy by 1 year will cause the birth rate to decrease by 0.89
(Intercept) LifeExpectancy 83.4090 -0.8895
Give a 95% confidence interval for the true slope.
Is the slope significantly different from 0?
> qt(.975,5)  2.570582
We are 95% confident that the true slope, regressing temperature on cricket chirp rate, is between 0.194 and 0.266 degrees per chirp per minute.
There is strong evidence that the slope is significantly different from 0, and that there is an association between cricket chirp rate and temperature.
If results are very significant, it doesn’t really matter if you get the exact p-value… you come to the same conclusion!