Wk8
Study design and validity of causal effect
Differences between controlled and quasi-experimental experiments
Clinical vs. Community trials
Blinding and crossover
Ethical aspects of conducting clinical trials
Measures of effect-calculation and interpretation
Statistical measures of effect
Instructions:
Answer the following Epidemiology questions below. If calculations are involved, be sure to show your work for full credit.
- (1 point) List one strength and one weakness of the experimental study design.
Answer:
- (1 point) Explain the difference between experimental and quasi-experimental study designs.
Answer:
- (1 point) Researchers want to study the impact of implementing an education program on the benefits of consuming more fresh fruits and vegetables among adults working for large employers in Green Giant City (population 3,000,000 persons). There are eight large businesses in the city that employ a total of 100,000 employees, four of which receive the intervention. Describe one method you could use to evaluate the outcome of this quasi-experimental study.
Answer:
Questions 4-7 (4 points) In the next four questions, identify the study design in each of the following scenarios. (Note: these questions draw from information presented in Chapters 6, 7 and 8. They are presented in multiple choice format in Canvas.)
- Researchers compare the effectiveness of two treatments for hypertension by randomly assigning patients with hypertension to receive the standard treatment or a newly-developed treatment for hypertension.
- Researchers want to study the impact of implementing a lunch-hour walking program on average Body Mass Index (BMI) measurements among adults working in Pedestrian City (population 2,000,000 persons). There are eight large businesses in the city that employ 5,000 or more employees. Employees the businesses get an extra 30 minutes added to their lunch hour 3 days a week to walk, run or engage in some other type of aerobic exercise activity. No intervention is implemented in the other four businesses.
- Phase III trial of a new vaccine developed to prevent Hepatitis C infection.
- Researchers wanted to determine if an educational intervention would improve rates of Hepatitis B vaccination in new-born babies in the United States. A study population of two similar urban communities were assigned one of two types of educational information about the benefits of vaccinating babies against Hepatitis B, starting at birth: 1) in one community, expectant mothers received information from their primary health care provider during a prenatal visit; 2) in the other community received additional, more comprehensive information about the benefits of their baby being vaccinated at a free “lunch-and-learn”-style training were held, targeting expectant mothers and their families (presented by health education specialists).
Chapter 9
- (4 points) [Note: check out Question 10 in the textbook for hints.]
A cohort study was conducted to investigate the possible association between energy drink consumption and insomnia in a population-based sample of adults.
| Insomnia | ||||
| Energy Drink Consumption | Yes | No | Total | |
| Yes | 200 | 1,800 | 2,000 | |
| No | 100 | 9,900 | 10,000 | |
Using the data in the table above, calculate the following:
- What is the Relative Risk of insomnia associated with energy drink consumption?
Answer:
- What is the risk (rate) difference?
Answer:
- What proportion of the rate of insomnia in the exposed group is due to energy drink consumption? (etiologic fraction)
Answer:
- What percentage of insomnia could be reduced in the population by eliminating energy drink consumption?
Answer:
- (6 points) [Note: check out Questions 3-8 in the textbook for hints. Use 10,000 as the denominator for each of the calculations.]
The rate of Awful Disease per 10,000 population is 500 among persons with Risk Factor A (exposed), and 56 among persons without Risk Factor A (non-exposed). The rate of Unpleasant Disease per 10,000 is 350 among persons with Risk Factor A (exposed) and 295 among persons without Risk Factor A (non-exposed). The prevalence of Risk Factor A in the population is 30%. Based on this information, answer the following six questions:
- What is the Relative Risk of having Awful Disease for persons with and without Risk Factor A?
Answer:
- What is the Relative Risk of having Unpleasant Disease for persons with and without Risk Factor A?
Answer:
- What is the etiologic fraction of Awful Disease for persons due to Risk Factor A? Answer:
- What is the etiologic fraction of Unpleasant Disease due to Risk Factor A?
Answer:
- What is the population etiologic fraction of Awful Disease due to Risk Factor A? Answer:
- What is the population etiologic fraction of Unpleasant Disease due to Risk Factor A? Answer:
- (1 point) Based on your calculations in Question 9, Risk Factor A seems more likely to be causally related to Awful Disease or Unpleasant Disease? Why?
Answer:
- (1 point) The confidence interval for the Relative Risk of contracting Awful Disease if exposed to Risk Factor A is (2.1, 11.7). Does it support the hypothesis that the association between Risk Factor A and Awful Disease statistically significant? Why or why not?
Answer:
- (1 point) Does sample size have an effect on the ability to detect differences between an intervention and a control group?
Answer:
