1. An investigator conducts a study to investigate whether mean peak expiratory flow (PEF) is lower 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? Run the appropriate test at a=0.05.
|
Group
|
Number of Children
|
Mean PEF
|
StdDev PEF
|
|
Chronic Bronchitis
|
25
|
281
|
68
|
|
No Chronic Bronchitis
|
25
|
319
|
74
|
What are the null and alternative hypotheses?
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1.
|
Ho: µ1 = µ2 vs. H1: µ1 ≠ µ2
|
|
2.
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Ho: µ1 = µ2 vs. H1: µ1 < µ2
|
|
3.
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Ho: µd = 0 vs. H1: µd ≠ 0
|
|
4.
|
Ho: p=0.5 vs. H1: p>0.5
|
2. What is the appropriate test statistic for #5?
|
1.
|
matched z-test
|
|
2.
|
independent samples z-test
|
|
3.
|
matched t-test
|
|
4.
|
independent samples t-test
|
|
5.
|
chi-square test of independence
|
3. You compute the test statistic for the above study and find that the probability of obtaining a value this large is less than .05. What is your decision?