Question 3
An investigator conducts a study to investigate whether there is a difference in means PEF in
children with chronic bronchitis as compared to those without. Data on PEF are collected and
summarized below. Based on the data, is there statistical evidence of a lower mean PEF in
children with chronic bronchitis as compared to those without? Apply the two sample t test at
alpha = 0.05.
Group
Number of children
Mean PEF
Std Dev PEF
Chronic Bronchitis
25
281
68
No chronic bronchitis
25
319
74

2. Upper limit 95% CI =
349.55

3. Lower limit CI 95% =
288.45

4. Based on comparing the critical the upper and lower limits of the confidence interval for the
mean of PEF for children with no Chronic Bronchitis to the mean PEF for children with

Question 4
The following are body mass index (BMI) scores measured in 12 patients who are free of diabetes and
particularly in a study of risk factors for obesity. Body mass index is measured as the ratio of weight in
kilograms to height in meters squared. Generate a 95% confidence interval estimate of the true BMI. 25,
27, 31, 33, 26, 28, 38, 41, 24, 32, 35, 40

8. Which of the following is true?

3