Introduction to linear regression

Correlation, Part I. What would be the correlation between the ages of husbands and wives if men always married woman who were

1. 3 years younger than themselves?

2. 2 years older than themselves?

3. half as old as themselves?

Units of regression. Consider a regression predicting weight (kg) from height (cm) for a sample of adult males. What are the units of the correlation coefficient, the intercept, and the slope?

Over-under, Part I. Suppose we fit a regression line to predict the shelf life of an apple based on its weight. For a particular apple, we predict the shelf life to be 4.6 days. The apple’s residual is -0.6 days. Did we over or under estimate the shelf-life of the apple? Explain your reasoning.

The Coast Starlight, Part II. Exercise 8.11 introduces data on the Coast Starlight Amtrak train that runs from Seattle to Los Angeles. The mean travel time from one stop to the next on the Coast Starlight is 129 mins, with a standard deviation of 113 minutes. The mean distance traveled from one stop to the next is 108 miles with a standard deviation of 99 miles. The correlation between travel time…

Murders and poverty, Part II. Exercise 8.25 presents regression output from a model for predicting annual murders per million from percentage living in poverty based on a random sample of 20 metropolitan areas. The model output is also provided below.

1. What are the hypotheses for evaluating whether poverty percentage is a significant predictor of murder rate?

2. State the conclusion of the hypot…

True / False. Determine if the following statements are true or false. If false, explain why.

1. A correlation coefficient of -0.90 indicates a stronger linear relationship than a correlation of 0.5.

2. Correlation is a measure of the association between any two variables.