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.
D. This study does not suggest that there is a difference in mean birth weights when we
compare smokers to non-smokers.