- We regress the frequency of car accidents (number per week) on frequency of rainy days (number of days per week), giving us this regression: Accidents = α + δRain + ε. Select if the following statements are true or false.
- Traffic volume is negatively correlated with rainy days and positively correlated with the number of accidents. Omitted variable bias is negative, so including traffic volume as a covariate will make δ more positive.
- Traffic volume is negatively correlated with accidents and positively correlated with rainy days. Omitted variable bias is negative, so including traffic volume as a covariate will make δ more positive.
- Traffic volume is negatively correlated with accidents and positively correlated with rainy days. Omitted variable bias is negative, so including traffic volume as a covariate will make δ more negative.
- Traffic volume is negatively correlated with rainy days and positively correlated with the number of accidents. Omitted variable bias is negative, so including traffic volume as a covariate will make δ more negative.
- We regress shark attacks on ice cream sales. How do we calculate our regression coefficient?
- Var(Shark attacks) / Cov(Shark attacks, Ice cream)
- Cov(Shark attacks) / Cov(Ice cream)
- Cov(Shark attacks, Ice cream) / Var(Ice cream)
- None of the above
- We regress the chance of experiencing a heart attack on age using a nonlinear model, giving us the following regression: HeartAttack = α + β1Temperature + β2Temperature2 + ε. We find that both β1 and β2 are positive numbers. Which of these statements is true?
- Your risk of heart attack falls as the temperature increases, until a certain point, after which your risk of heart attack begins to rise again, giving us a U-shaped curve.
- Your risk of heart attacks rises as temperature increases until a certain point, after which your risk of heart attack begins to decrease, giving us an inverse U-shaped curve.
- Your risk of heart attack increases exponentially as the temperature increases.
- Your risk of heart attack decreases exponentially as the temperature increases.
- We regress income on education and include a variety of covariates, as seen in the following regression: Income = α + β1Batten + β2Nonwhite + β3Female + β4ParentsIncome + ε. Which of these statements is true regarding α?
- Alpha is the average parental income for non-white women who didn’t who to Batten.
- Alpha is the average income for people who didn’t go to batten who are white and non-female with a parental income of of $0.
- Alpha is the average income for Non-white men with a family income of $0 that did go to Batten.
- Alpha is the average income for people who go to Batten, who are non-white, female and have some average parental income.
- We regress income on weight, giving us the following regression: Income = 5,000 + 100Weight – .25Weight2 + ε. At what weight does the effect of weight on income changes sign?
- 20 pounds
- 400 pounds
- 200 pounds
- None of the above
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