QUESTION 4 In a study of the impact of smoking on birth weight, researchers anal
ID: 3307149 • Letter: Q
Question
QUESTION 4
In a study of the impact of smoking on birth weight, researchers analyze birth weights (in grams) for babies born to 189 women who gave birth in 1989 at a hospital in Massachusetts. In the group, 74 of the women were categorized as smokers and 115 as non-smokers. The difference in the two sample mean birth weights (non-smokers minus smokers) is 281.7 grams and the 95% confidence interval is (76.5, 486.9). Which gives the best interpretation of what we can conclude about the impact of smoking on birth weight?
A. We are 95% confident that on average, smoking causes lower birth weights of between 76.5 grams to 486.9 grams.
B. There is a 95% chance that if a woman smokes during pregnancy her baby will weigh between 76.5 grams to 486.9 grams less than if she did not smoke.
C. Smoking is associated with lower birth weights. When smokers are compared to non-smokers, we are 95% confident that the mean weight of babies of non-smokers is between 76.5 grams to 486.9 grams more than the mean weight of babies of smokers.
D. This study does not suggest that there is a difference in mean birth weights when we compare smokers to non-smokers.
1 points
QUESTION 5
Do oddsmakers believe that teams who play at home will have home field advantage? Specifically, do oddsmakers give higher point spreads when the favored team plays home games as compared to when the favored team plays away games? Two samples were randomly selected from three complete National Football League seasons (1989, 1990, and 1991). The first sample consisted of 50 games, where the favored team played in a home game, while the second sample consisted of 50 games, where the favored team played in an away game. The oddsmakers point spreads (which are the number of points by which the favored team is predicted to beat the weaker team) were then collected.
Analyses were run. The following is the (edited) output for the test: .
From the output we learn that:
A. the data provide sufficient evidence to reject the H0; thus, we cannot conclude that the mean point spread of home games is higher than that of away games.
B. the data do not provide sufficient evidence to reject the H0; thus, we can conclude that the mean point spread for home games is higher than that of away games.
C. the data do not provide sufficient evidence to reject H0; thus, we cannot conclude that the mean point spread of home games is higher than that of away games.
D. the data provide sufficient evidence to reject H0; thus, we can conclude that the mean point spread for home games is higher than that of away games.
A. We are 95% confident that on average, smoking causes lower birth weights of between 76.5 grams to 486.9 grams.
B. There is a 95% chance that if a woman smokes during pregnancy her baby will weigh between 76.5 grams to 486.9 grams less than if she did not smoke.
C. Smoking is associated with lower birth weights. When smokers are compared to non-smokers, we are 95% confident that the mean weight of babies of non-smokers is between 76.5 grams to 486.9 grams more than the mean weight of babies of smokers.
D. This study does not suggest that there is a difference in mean birth weights when we compare smokers to non-smokers.
Explanation / Answer
1 Answer
C. Smoking is associated with lower birth weights. When smokers are compared to non-smokers, we are 95% confident that the mean weight of babies of non-smokers is between 76.5 grams to 486.9 grams more than the mean weight of babies of smokers.
2. Answer
C. the data do not provide sufficient evidence to reject H0; thus, we cannot conclude that the mean point spread of home games is higher than that of away games.