1.Given that the researcher wants to be sure the mean difference in the change in hemoglobin levels has a margin of error no more than 0.2 g/dL and the difference in the stand deviation between the mean hemoglobin levels for the two forms of iron supplements used to treat anemia is 1.2 g/dL, what is the desired number of recruits for the study, assuming the individuals will participate in a crossover trial, if the study's attrition rate is expected to be .25?

n

= 139

n

= 186

n

= 554

n= 55,320

2.A clinical trial is conducted on a specific drug used to treat severe migraines and it is noted that approximately 25% of individuals in the study fail to respond to the drug and the medication appears to give them severe episodes of nausea and vomiting. Upon further examination it is revealed that these individuals carry a genetic marker, and the individuals who did not experience the side effects of nausea and vomiting did not have the same marker as those individuals who experienced the side effects. This is an example of which of the following?

Confounding

Effect modification

Selection bias

Differential bias

3.A clinical trial is being conducted in order to determine the efficacy of a new drug that will be used to treat type II diabetes. The efficacy of the medication will be determined by the blood glucose readings obtained from the patients. If the researcher wants a margin of error less than or equal to 5 mg/dL and the standard deviation for blood glucose readings among type II diabetics was previous documented as 15 mg/dL, how many patients should be recruited for each group of individuals in the study assuming a 95% confidence interval will be used to quantify the mean difference in blood glucose scores between the control group and the treatment group?

n

for the treatment group = 32 and n for the control group = 13

n

for the treatment group = 33 and n for the control group = 33

n

for the treatment group = 70 and n for the control group = 70

n

for the treatment group = 1729 and n for the control group = 1729

4.A clinical trial is being conducted in order to determine the efficacy of a new drug that will be used to treat Crohn's disease. The efficacy of the medication will not only be determined by the physical improvement of symptoms but will also be determined by using a blood test to examine the concentration C-reactive protein (an inflammatory marker) in an individual's blood. If the researcher wants a margin of error for the level of C-reactive protein to be less than or equal to 2.9 mg/dL and the standard deviation for C-reactive protein concentrations among Crohn's disease patients was previously documented at 10.1 mg/dL, how many patients should be recruited for each group of individuals in the study, assuming a 95% confidence interval will be used to quantify the mean differences between the control group and the treatment group?

n

for the treatment group = 12 and n for the control group = 12

n

for the treatment group = 14 and n for the control group = 14

n

for the treatment group = 47 and n for the control group = 47

n

for the treatment group = 94 and n for the control group = 94

5.A researcher suspects the mean trough (the lowest dosage of medication required to see clinical improvement of symptoms) level for a medication used to treat arthritis is higher than was previously reported in other studies. If previous studies found the mean trough level of the population to be 3.7 micrograms/mL, and the researcher conducts a study among 93 newly diagnosed arthritis patients and finds the mean trough to be 6.1 micrograms/mL with a standard deviation of 1.2 micrograms/mL, the researcher's hypothesis, for a level of significance of 1%, should resemble which of the following sets of hypothesis?

H₀: = 3.7 micrograms/mL; H₁: > 3.7 micrograms/mL; alpha= .01

H₀: > 3.7 micrograms/mL; H₁: = 3.7 micrograms/mL; alpha= .01

H₀: = 3.7 micrograms/mL; H₁: > 3.7 micrograms/mL; alpha= .99

H₀: > 3.7 micrograms/mL; H₁: = 3.7 micrograms/mL; alpha= .99

6.A researcher wants to estimate the impact prenatal care during pregnancy can have on anemia rates in pregnant mothers by conducting a retrospective case-control study on new moms. If the prevalence of anemia is approximately 39.7%, how many individuals should the researcher recruit to participate in the study if the researcher wants to be 95% confident that the margin of error is no more than 3.0%?

n

total = 2044; n control group = 1,022; n case group = 1,022

n

total = 2044; n control group = 812; n case group = 1,232

n

total = 4088; n control group = 1,623; n case group = 2,465

n

total = 4088; n control group = 2,044; n case group = 2,044

7.A researcher suspects the mean trough (the lowest dosage of medication required to see clinical improvement of symptoms) level for a medication used to treat arthritis is higher than was previously reported in other studies. If previous studies found the mean trough level of the population to be 3.7 micrograms/mL, and the researcher conducts a study among 93 newly diagnosed arthritis patients and finds the mean trough to be 6.1 micrograms/mL with a standard deviation of 2.4 micrograms/mL, for a level of significance of 1%, what should the researcher's decision rule look like?

Reject H₀ if z is less than or equal to -2.326.

Reject H₀ if z is greater than or equal to 2.326.

Reject H₀ if z is less than or equal to -2.576.

Reject H₀ if z is greater than or equal to 2.5760

8.Another researcher also decides to conduct a study to observe the association between smoking cessation among long-term smokers and obesity since it has been previously well documented in the literature that smokers tend to gain weight when they stop smoking. The researcher notes that among the individuals who gain weight, many of them have developed heart problems or other medical problems that typically prevent them from exercising as much as their counterparts. In this case the researcher notes that individuals who have developed the heart problems or other medical problems causing them to gain weight also came from family with a high prevalence of risk-taking behaviors, so they consume unhealthy diets and are less likely to exercise in general than their counterparts. This is an example of which of the following?

Confounding

Effect modification

Recall bias

Socially desirable response bias

9.What is the odds ratio for a study with a logistic regression coefficient -0.2524?

1. 0.78
2. 1.00
3. -0.78
4. -2524