For each of the following examples identify the study design used and list all the possible measures of association or excess risk that could be calculated (do not calculate): Comparison of 50 people with brain cancer and 100 people without brain cancer to assess the association of brain cancer in those regularly using a mobile phone. (2 pts) A study of 10,000 people 70-80 years of age initially without dementia who are then followed during a ten-year period to identify risk factors for developing dementia. (3 pts)
Added by Lourdes E.
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- The first example involves comparing two groups: 50 people with brain cancer (cases) and 100 people without brain cancer (controls) to assess the association with mobile phone use. This is a **case-control study** design. Show more…
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Suppose that in 1998, researchers hypothesized that communication ability and skill in young adulthood were related to Alzheimer's Disease. To test this, they evaluated handwritten essays completed by a group of 350 participants in 1930. By careful review of these writing samples, the researchers categorized all 350 as either having a high error profile (N=150) or a low error profile (N=200). Using surveillance of death certificates and other methods, the researchers verified the vital status of each participant through 1998. An accounting of all deaths is produced in Table 1 below. Table 1: Cause of Death and Year by Handwriting Profile Status High error profile (N=150) Low error profile (N=200) Cause of Death # of Deaths Year of Death Cause of Death # of Deaths Year of Death Alzheimer's Disease 4 1980 Alzheimer's Disease 1 1985 Alzheimer's Disease 5 1985 Alzheimer's Disease 3 1990 Alzheimer's Disease 6 1990 Alzheimer's Disease 4 1995 Alzheimer's Disease 5 1995 Heart Disease 8 1980 Heart Disease 10 1980 Heart Disease 10 1990 Heart Disease 15 1995 Other 20 1960 Other 25 1960 Other 10 1970 Other 30 1970 What is the study design used in this example? Compute the incidence density of Alzheimer's disease death for those with a high error profile. Show your work. (Use 10,000 person-years as the multiplier) Compute the incidence density of Alzheimer's disease death for those with a low error profile. Show your work. (Use 10,000 person-years as the multiplier) Compute the incidence density ratio for the risk of Alzheimer's disease death associated with a high error communication profile. Interpret it. Incidence density ratio calculation: Interpretation of the incidence density ratio: Use data from this study to complete the 2x2 table below and compute an odds ratio for the association of a high error communication profile with death from Alzheimer's disease. Show a clearly labeled 2x2 table. Interpret the OR. Calculation of the OR: Given the study design, does this measure of association tell you the odds of disease or the odds of exposure? Interpretation of the OR.
Supreeta N.
A study of cell phones and the risk of brain cancer looked at a group of 469 people who had brain cancer. The investigators matched each cancer patient with a person of the same sex, age, and race who did not have brain cancer, and then asked about their use of cell phones. Result: "Our data suggest that use of handheld cellular telephones is not associated with risk of brain cancer." (a) What type of study is this? Observational study: prospective Observational study: retrospective Observational study: cross-sectional Experiment: matched pairs design Experiment: randomized block design Experiment: completely randomized design
Ariana N.
1. Several epidemiologists conducted a cohort study of the effect of mercury exposure on the development of brain cancer. Subjects were followed for ten years. There were a total of 150,000 people in the study. Among the subjects, 76,000 were exposed to mercury and the rest were not. 52,000 of those exposed to mercury developed brain cancer, and only 1,200 of those unexposed to mercury developed brain cancer. Assume that 30% of people in Rhode Island are exposed to mercury. a. Set up the two by two table (2 points). b. What is the Odds Ratio (also interpret; 2 points)? c. What is the Relative Risk (also interpret; 2 points)? 2. A five year study was conducted among 5,000 men older than 65 years to examine the relationship between heavy alcohol consumption and the onset of atrial fibrillation. The men were assessed each year. Men who drank heavily contributed a total of 12,500 person-years of observation and 250 of those who drank heavily developed atrial fibrillation. A total of 24,000 person-years were observed for the entire study. And 100 men who did not drink heavily developed atrial fibrillation. a. Set up the two by two table (2 points). b. What is the Rate Ratio (also interpret; 2 points)?
Lainey R.
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