Reference no: EM132298332

Biostatistics

1. Suppose you wish to compare the mean years of education of all faculty in the Epidemiology and Biostatistics department to the mean years of education of all faculty in the Community and Family Health department at USF. Which is the most appropriate technique for gathering the needed data?

2. In one study on the effect of Dyazide on blood pressure level, 25 subjects were randomly chosen to receive Dyazide and 25 were chosen to receive a placebo. These subjects were later examined to check for differences in their blood pressure levels. In a second study, 200 subjects who reported taking Dyazide for a long period of time had their blood pressure levels compared with those of 200 people who had never taken Dyazide.
Which of the following statements is correct?

3. The duration of length of stay at Tampa Bay Nursing Home is

4. Which of the following methods of graphing sample data can help you in determining the shape of a frequency distribution for the variable height (measured in inches)?

5. A researcher would like to study BMI levels in adults 20-40 years of age. She selected 9 patients and found their BMI values to be: 25, 19, 20, 21, 32, 37, 22, 27, 24
The mean BMI level of this group of patients is

6. A researcher would like to study BMI levels in adults 20-40 years of age. She selected 9 patients and found their BMI values to be: 26, 20, 28, 32, 29, 38, 21, 25, 23
The standard deviation of BMI levels of this group of patients is

7. A sample of 1000 subjects is stratified gender and physical activity level as follows:

	Physical Activity Level
Gender	Low	High	Total
Male	100	500	600
Female	300	100	400
Total	400	600	1000

In a random selection of a subject from the study population, what is the probability that the person has low physical activity levels?

8. The Table below shows data on age group by smoking status that was collected by a study looking at the associations between smoking and age. What is the probability of selecting a current smoker between the ages of 51 to 60?

9. Five hundred women are enrolled in a study to evaluate the accuracy of a test for pregnancy. 200 of the women were actually pregnant. 170 of the pregnant women had a positive test as did 140 of the women who were not pregnant. What is the probability (i.e., specificity) that a woman tested negative on a test given that she is not pregnant?

Test	Pregnant?
	Yes	No	Total
+	170	140	310
-	30	160	190
Total	200	300	500

10. A graduate student is registering for 3 courses in one semester. X=the number of courses that are full at the time of registration. The random variable X has a probability distribution as follows

x	0	1	2	3
p(x)	0.55	0.25	0.15	0.05

The probability that less than one of the classes are full at the time of registration [P(X < 1)] is equal to

11. The Central Limit Theorem states that:

12. Which of the following statements are true regarding Type I or Type II errors?

13. In One Sample Proportion test, it is important to convert the sample proportion to a z-score first. In this example, we selected a random sample of size 140 from a pool of university students and asked whether they use the university gym on a regular basis. Ninety-five replied yes. Assuming that the population proportion under the null hypothesis is 50%, what is the z-score for the sample proportion?

14. To investigate the prevalence rate of diabetes among men in Florida, we drew a random sample of 75 men from that population and among them 15 people had diabetes. For the following hypotheses, what would be your conclusion based on the information provided? The level of significance (alpha level) is 0.05. (Hint: Depending on the direction of the alternative test, use 1.96 or -1.96 as the critical z-value)
Ho: P = 0.2 (Null)
Ha: P > 0.2 (Alternative)

15. Researchers want to test the effectiveness of a new pain medication. Four hundred people were recruited to participate in the clinical trial. In clinical testing, 49 out of 210 people taking the medication reported pain symptoms. Of the other 190 people receiving a placebo, 140 reported pain symptoms. What is the estimated standard error of the difference of the two sample proportions based on pooled sample proportion?

16. It is known that the population standard deviation of weight among females is 30. Assuming that we have a random sample of 210, what is the standard error of the average weight among women of a sample of this size?

17. It is known that the population standard deviation of weight among females is 30. Assuming that we have a random sample of 122 and a sample mean of 129, what would be your 90% confidence interval estimate of the population mean weight? (Hint: use 1.65 as the critical z-value)

18. Fourteen students were randomly selected from the College of Public Health and their diastolic blood pressure was tested. The sample mean and standard deviation were 81.6 mmHg and 2.3 mmHg respectively. What is the obtained t-score for this sample under the null hypothesis Ho: µ = 80?

19. To compare the treatment effects of two interventions, two independent samples of patient medical data were collected. The sample sizes are 23 and 21 respectively. Assuming that the two populations shared the same variance, the researchers decided to conduct a two independent samples test for the means. What would be the number of degrees of freedom for the obtained t statistic with these sample sizes?

20. Researchers want to test the effectiveness of a new pain medication. Four hundred people were recruited to participate in the clinical trial. In clinical testing, 48 out of 180 people taking the medication reported pain symptoms. Of the other 220 people receiving a placebo, 67 reported pain symptoms. Combining the two samples together, what is the overall proportion of those who reported pain symptoms among all participants?

21. For correlation coefficients, the value of r indicates:

22. Which of the following assumptions concerning the probability distribution of the random error term in a simple regression model is stated incorrectly?

23. Which of the following indicates a weak positive correlation?

24. A biostatistician finds the relationship between the number of weeks (X) spent in a hospital and number of seizures per week (Y) and is described by the following equation: FinalExamQ24b.JPG. This is based on a sample size of 50 patients and the associated coefficient of correlation is r = -.84.

Using this information above, answer the following question: How do you interpret r = -.93?

25. The probability that a person does not have a disease given that he/she tested negative on a screening test is called the