A pilot study to evaluate the serum alpha tocopherol levels (serum vitamin E) was conducted to evaluate the toxicity among 12 people who regularly take vitamin-E supplements. The vitamin E levels for the 13 participants are listed below. lithe level of alpha tocopherol in the general population 860 μg/dL, conduct a hypothesis test to determine if those who take supplements have significantly greater levels of serum alpha tocopherol with alpha = 5% and the sample standard deviation is 487.15 μg/dL.
565 2010 1350 780 1505 1235 810 1990 1105 650 1010 1570
1. What hypothesis test is appropriate to answer this research question?
a. One-sample Z test
b. One-sample t Test
c. Matched t Test
d. Chi-Square test for association/independence
2. What is the alternative hypothesis?
a. There is no significant difference in serum alpha tocopherol levels.
b. There is a significant difference in serum alpha tocopherol levels.
c. Those who take vitamin-E supplements have significantly greater alpha tocopherol levels.
d. Those who take vitamin-E supplements have significantly lower alpha tocopherol levels.
3. What is the critical value?
a. +1.96
b. +1.7959
c. +1.645
d. +2.2010
4. What is the sample mean?
5. What is the test statistic rounding to two decimal places?
6. True or False: Fail to reject H0 as the test statistic does not fall within the rejection region.
7. What is the lower bound of the 95% confidence interval given the information above? Round to two decimal places.
8. What is the upper bound of the 95% confidence interval given the information above? Round to two decimal places.
9. Suppose the investigator of the pilot study wants to expand to a larger study to make sure 80% power is achieved. What sample size is needed to detect a difference in means of 75 given the standard deviation of 487.15?
10. What sample size is needed to ensure adequate power based on question 9 if it is suspected there will be 15% attrition?
Patients with heart failure, diabetes, cancer, and lung disease who have various infections from gram negative organisms often receive aminoglycosides. One of the side effects of aminoglycosides is nephrotoxicity (possible damage to the kidney). A study was performed comparing the nephrotoxicity (rise in serum creatinine of at least 0.5 mg/dL) for the aminoglycoside gentamicin. The following results were obtained:
|
|
Rise in serum creatinine (> 0.5)
|
No rise in serum creatinine (< 0.5)
|
|
Gentamicin (G)
|
44
|
77
|
|
No Gentamicin (G)
|
21
|
71
|
Test the hypotheses that there is a significant relationship between gentamicin and nephrotoxicity using a chi-square test with alpha = 5%.
11. What is the alternative hypothesis?
a. There is no association between gentamicin and nephrotoxicity
b. There is an association between gentamicin and nephrotoxicity
c. Those who take gentamicin have greater serum creatinine levels
d. Those who take gentamicin have lower serum creatinine levels
12. What is the critical value?
13. What is the expected value of those who take gentamicin and have a rise in serum creatinine? Round to two decimal places.
14. What is the expected value of those who take gentamicin and have no rise in serum creatinine? Round to two decimal places.
15. What is the expected value of those who do not take gentamicin and have a rise in serum creatinine? Round to two decimal places.
16. What is the expected value of those who do not take gentamicin and have no rise in serum creatinine? Round to two decimal places.
17. What is the test statistic? Round to two decimal places.
18. True or False: There is a significant association between gentamicin and nephrotoxicity.
19. What is the relative risk (RR) of having a rise in serum creatinine levels given a patient received gentamicin compared to not receiving gentamicin?
20. Suppose sex is suspected to be a confounder and the breakdown of gentamicin vs. creatinine levels are given below. What is the RRCMH?
|
Male
|
Rise in serum creatinine 0.5)
|
No rise in serum creatinine (<0.5)
|
|
Gentamicin (G)
|
15
|
26
|
|
No Gentamicin (G)
|
6
|
32
|
|
Female
|
Rise in serum creatinine 0.5)
|
No rise in serum creatinine(<0.5)
|
|
Gentamicin (G)
|
29
|
51
|
|
No Gentamicin (G)
|
15
|
39
|
21. True or False: Comparing RRcrude (from Q19) to RRCMH, sex does not appear to be a confounder.
The table gives the age and left ventricular ejection fraction for 15 patients with acute dilated cardiomyopathy. The mean age is 43.13 (s = 16.61) and the mean LVEF is 0.26 (s = 0.07).
|
Patient Number
|
Age
x
|
Left ventricular
ejection fraction
(LVEF), y
|
|
1
|
35
|
0.19
|
|
2
|
28
|
0.24
|
|
3
|
25
|
0.17
|
|
4
|
75
|
0.40
|
|
5
|
42
|
0.40
|
|
6
|
19
|
0.23
|
|
7
|
54
|
0.20
|
|
8
|
35
|
0.20
|
|
9
|
30
|
0.30
|
|
10
|
65
|
0.19
|
|
11
|
26
|
0.24
|
|
12
|
56
|
0.32
|
|
13
|
60
|
0.32
|
|
14
|
47
|
0.28
|
|
15
|
50
|
0.24
|
22. Calculate the sample correlation coefficient rounding to two decimal places. Note: Use the provided mean and standard deviation as a shortcut to the calculations.
23. The correlation between age and LVEF is
a. strong positive
b. moderately strong positive
c. moderate strong inverse
d. weak positive
24. What is the slope of the corresponding regression line (i.e. b1)? Round to 3 decimal places.
25. What is the y-intercept of the corresponding regression line (i.e. b0)? Round to 3 decimal places.
26. Given a 30 year-old patient with acute dilated cardiomyopathy, what is their predicted left ventricular ejection fraction? Round to 3 decimal places.
27. Suppose the investigator established the regression line that also includes race:
y = 0.146 + 0.0360xBlack =-1, White = 0+ 0-002xage
What is the predicted left ventricular ejection fraction for a black 30 year-old patient with acute dilated cardiomyopathy?
An experiment was conducted to study responses to different methods of taking insulin in patients with type I diabetes. The percentages of glycosolated hemoglobin initially and 3 months after taking insulin by nasal spray are given in the table below.
|
Patient Number
|
Before
|
3 Months After
|
|
1
|
11.0
|
10.2
|
|
2
|
7.7
|
7.9
|
|
3
|
5.9
|
6.5
|
|
4
|
9.5
|
10.4
|
|
5
|
8.7
|
8.8
|
|
6
|
8.6
|
9.0
|
|
7
|
11.0
|
9.5
|
|
8
|
6.9
|
7.6
|
Conduct a two-sided Wilcoxon Sign Rank Test with alpha = 5% to determine if there is a significant difference in glycosolated hemoglobin after taking insulin by nasal spray.
28. What is the critical value?
29. What is the sum of the positive ranks (i.e. W+)?
30. What is the sum of the absolute value of negative ranks (i.e. W-)?
31. What is the test statistic?
32. True or False: There is no significant difference in glycosolated hemoglobin in patients 3 months after taking insulin by nasal spray.
33. The ANOVA Post Hoc Analyses article discusses the liberality of the variety of the post hoc tests once a significant difference has been found after conducting an ANOVA. What does being a "liberal" test mean?
a. Likely to result in a Type II error
b. Lower power is adequate to conduct the post hoc
c. Likely to result in a Type I error
d. Smaller sample size is adequate to conduct the post hoc
34. What post hoc analysis mentioned in the paper is the most liberal?
a. Tukey-Kramer HSD
b. Fisher PLSD
c. Scheffe
d. SNK