The main question of interest is whether babies born to smoking mothers tend to
ID: 3075247 • Letter: T
Question
The main question of interest is whether babies born to smoking mothers tend to have lower birth weights. The following figure shows a side-by-side comparison of the two distributions from this data set.
(sorry I'm not sure how to capture the box and whisker plot)
A two-sample t-test in R gave the following output:
Welch Two Sample t-test
data: Weight by SmokingStatus
t = 1.3865, df = 18.42, p-value = 0.1817
alternative hypothesis: true difference in means is not equal to 0 95 percent confidence interval:
-131.3122 646.6612
sample estimates:
mean in group NonSmoker mean in group Smoker
3258.941 3001.267
(c) On average, how much lower are birth weights for smokers compared to nonsmokers? [1 mark] (d) Summarise the conclusions from the t-test. [2 marks] Weight (g) 1000 2000 3000 4000
Explanation / Answer
(C) answer=3258.941 - 3001.267=257.674
(D) since p-value is greater than the level of significance=alpha=0.05,
so we fail to reject the null hypothesis H0: mean(NonSomoker)=mean(Smoker) and conclude that there is no statistical difference between average wieght of Non smoker and smoker
also confidencen interval doesnot contain zero(0) so we accept (fail to reject) null hypotheis H0
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