• Two-sample Non-parametric Test
Now, we examine the relationship between cry time and group among infants at Northbay.
1. Suppose we wish to perform a two-sample test, but we do not want to make any normality (or other strong parametric) assumptions. Conduct an appropriate non-parametric test to test whether the distribution of cry time is the same in both groups at the 0.05 level of significance.
What is your p-value?
unanswered
Your conclusion from the test?
there is evidence that the *means* of the two groups are different (specifically, there is evidence that the mean is higher in the control group) there is not evidence that the *means* of the two groups are different none of the above
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• 2. Assuming randomization was successful and all participants complied with their assigned exposure, which of the following should we be concerned about:
Confounding by sex of the infant Confounding by the amount of pain experienced by the infant Effect modification by sex of the infant Misclassification of the exposure status of the infant
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• Exploratory Analysis
Before jumping into analyzing the babies.dta dataset, first explore the dataset using summary statistics and graphical analyses.
1. Make a boxplot of cry time by group. According to the boxplot, which group has more variability in cry time?
control intervention
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• 2. Using the central limit theorem, construct a 95% confidence interval for the average total cry time for infants in the control group and infants in the intervention group. For this question only, assume that the standard deviation of cry time within each group is known and is equal to 22 seconds.
Control
Lower Bound
unanswered
Upper Bound
unanswered
Intervention
Lower Bound
unanswered
Upper Bound
8 answers