KP290 Chapter Notes - Chapter 6: Ecological Fallacy, Digital Camera, Randomized Controlled Trial

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cerisemallard21

28 Jun 2018

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Chapter 6:

Formal document: study protocol

1. Qualitative research methods: focus group

- Have a hypothesis, comparison group

- Allow statistical testing’s to determine a difference between groups

- To discover new knowledge and answer questions

2. Quantitative methods: experimental designs

- Randomized clinical trials

- Observational study design: cohort, cross-sectional, case-control, ecological study

Incidence rates: number of new cases of disease in a defined population at risk per unit time

Prevalence rates: number of existing cases in a defined population at risk during one point in

time

Experimental study designs: research has control over which study participants receive

- Exposure to the study (safe)

Randomized Controlled Trial

Usually therapeutic or beneficial effects

- Sometimes referred to as randomized clinical trial: helps evaluate prevention programs

to reduce disease

Experimental design (exposure)

Alternative (controls) or (placebo)

Prospective study = followed for a duration

Cohort Study

Without the disease of interest are sampled

Followed over time

Prospective study

Compared between exposed and unexposed

Population-based sampling: reflect the general population

Exposure based: exposure is uncommon or rare

Case control study

Controls (non-cases): free of the disease under the study being sampled

- Should be similar

- No measured follow up time

- Probability of exposure is calculated

- Good for studying rare and uncommon disease

- Cheaper and faster to complete then cohort

- More vulnerable to bias

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Document Summary

Allow statistical testing"s to determine a difference between groups. To discover new knowledge and answer questions: qualitative research methods: focus group. Have a hypothesis, comparison group: quantitative methods: experimental designs. Observational study design: cohort, cross-sectional, case-control, ecological study. Incidence rates: number of new cases of disease in a defined population at risk per unit time. Prevalence rates: number of existing cases in a defined population at risk during one point in time. Experimental study designs: research has control over which study participants receive. Sometimes referred to as randomized clinical trial: helps evaluate prevention programs to reduce disease. Without the disease of interest are sampled. Controls (non-cases): free of the disease under the study being sampled. Good for studying rare and uncommon disease. Exposure and disease are measured at the same time. Provide valuable information for a cohort or case control design. Ecological fallacy: group level and may not apply to the individual.

Related Questions

To complete the scenario section of the final, choose a scenario and paste it where indicated below. You may delete the other scenarios from the body of the exam. Answer the questions regarding the study you designed, giving the answers following each of the questions. If one of the questions isnât applicable to your study, respond N/A after the question. Any additional information about the study youâve designed can be added at the end of the required questions and will likely generate some extra points.

Design an epidemiological study for only ONE of the 6 scenarios below and provide at minimum the following information about your study:

Paste your scenario here

â¢ Study type (observational or experimental)

â¢ Study design (randomized trial, cohort, case-control, or cross-sectional)

â¢ Study hypothesis

â¢ Define your target population

â¢ Describe how you will recruit or identify study participants to best represent the target population

â¢ Describe the risks and benefits of participating in the study

â¢ Provide a case definition (e.g. in a cohort study, how will you diagnose those who become ill, in a case-control or cross-sectional study, what characteristics does the participant need to have to be considered a case)

â¢ Describe exposures or risk factors and how you will measure them

â¢ Describe exclusion criteria (e.g. in a prospective cohort study, a person who tests positive for illness at or near baseline must be excluded)

â¢ Describe how you will collect data for your study (survey, medical records, laboratory tests, etc.)

â¢ Divide subjects as appropriate for your study design (i.e. exposed/unexposed, case/control)

â¢ Describe outcome measure for study, how itâs calculated, and how itâs to be interpreted (you donât need to actually do calculations, but provide the equations and give an example of how theyâre interpreted): For example: RR=a/(a+b) interpreted as the risk of lung cancer in smokers is X times greater (or less) than it is in non-smokers

â¢ Give justification for your study design (tell why you chose that particular study design, why it is appropriate, and what you hoped to learn from doing the study)

â¢ Brief discussion of study strengths and weaknesses including a discussion of causal hypotheses and biases as they relate to your study design

Scenario 1: A new vaccine (NoBola) has been developed to prevent Ebola. Design a study that will indicate whether or not NoBola is associated with a reduction in Ebola cases in parts of the world where Ebola is endemic.

1. The risk of acquiring disease is measured by the a. Incidence rate b. Incidence rate times the average duration of the disease c. Incidence rate divided by the prevalence rate d. Prevalence rate e. Prevalence rate times the average duration of the disease

2. The strength of an association between a factor and a disease is best measure by a. Incubation rate b. Incidence of the disease in the total population c. Prevalence of the factor d. Attributable risk e. Relative risk

3. Case fatality rate for a given disease refers to a. The crude mortality rate per 100,000 population b. Cause-specific mortality rate due to the disease c. A fatal outcome of any disease d. The percentage of deaths among cases of the disease e. The proportion of deaths due to the disease among all deaths from all causes

4. An investigator is interested in etiology of neonatal jaundice. To study this condition, he selected 100 children who were diagnosed with this condition and 100 children born in the same period and in the same hospital who did not have a diagnosis of neonatal jaundice. He then reviewed the obstetrical and delivery records of their mothers to determine various prenatal and perinatal exposures. This is an example of a(n): a. Cross-sectional study b. Case-control study c. Cohort study d. Clinical trial e. Experiment

5. Which of the following statements describes the major advantages of a randomized clinical trial? a. It avoids observer bias b. It lends itself to ethical justification c. It yields results replicable in other patients d. It rules out self-selection of participants to the different treatment groups d. It enrolls representative patients

6. A survey conducted in England revealed that of 224 families in which there had been a known case of poliomyelitis, 56 maintained parakeets as a family pet. In another British survey, 30 out of 99 poliomyelitis patients questioned kept parakeets. The inference that there is some relationship between the presence of a parakeet in a household and the occurrence of poliomyelitis among household members is a. Correct b. Incorrect because of failure to distinguish between incidence and prevalence c. Incorrect because a proportionate ratio is used when a rate is required to support the inference d. Incorrect because a failure to recognize a possible cohort phenomenon e. Incorrect because there is no control or comparison group.

7. An investigator determines the correlation coefficient between triglyceride levels and degree of atherosclerosis in sampled blood vessels to be +1.67. On the basis of this you would conclude that: a. Triglyceride level is a good predictor of atherosclerosis b. Triglyceride level is not a good predictor of atherosclerosis c. High triglyceride levels cause atherosclerosis d. Atherosclerosis cause high triglyceride levels e. The investigator has incorrectly determined the correlation coefficient

8. A screening test of known sensitivity and specificity is applied to two populations. The prevalence of the disease being screened for is 10% in population A and is 1% in population B. Which of the following is true? a. The percent of all negative tests that have false-negative results is lower in population A than in population B. b. Specificity is lower in population A than in population B. c. Reliability is higher in population A than in population B. d. The percent of all positive tests that have false-positive results is lower in population A than in population B. e. Specificity is higher in population A than in population B.

9. Serum cholesterol levels are obtained for four healthy men. The probability that all will fall below the 10th percentile of the distribution of cholesterol for healthy males is: a. 0.4 b. 1 â (0.1)4 c. (0.1)4 d. (0.9)4 e. Cannot be determined from these data

10. In a diabetes screening program, the screening level for a positive blood sugar level in test 1 is set at 160 mg/dl, and in test 2 at 130 mg/dl. The sensitivity is: a. Greater in test 1 b. Greater in test 2 c. Equal in test 1 and 2 d. Dependent on the size of the population being evaluated

Part II 1.The California Occupational Mortality study data set was employed to assess mortality data for the years 1979-1981. A 2% sample of employed persons from the 1980 census of California was used. It contains the occupation of each person who had died. This study, like any occupation-based study, is restricted to the work life span as far as age of subjects is concerned. This study used ages 16-64 years. Certain persons, because of their source of work, were excluded as subjects: homemakers, retired persons, students, disabled, military personnel, etc. Only main-stream-type employment was used in this study to establish occupations at risk for heavy alcohol drinking. Using the Table below, answer the following:

1.What occupations are most vulnerable to acquiring cirrhosis of the liver from heavy drinking?

2.List several of the occupations identified by the research studies that are more vulnerable to alcohol-induced, cirrhosis related deaths and that have the highest mortality rates.

3. What are possible confounding variables for the research in occupations and heavy drinking that lead to fatal diseases?

4. Based on available research data, develop and construct a web of causation along with the appropriate decision trees for occupational group-related alcohol deaths. Table. Alcohol Related Deaths in California, 1979-1981 Cirrhosis 5.5% Digestive organ cancers 5.7% Injuries 13.7% Suicide and homicide 5.% All other causes 64.9%

Zika and microcephaly Since May 2015, Brazil has experienced a significant outbreak of Zika virus. In recent years, Brazilian officials reported an increase in the number of babies born with microcephaly.

1. Briefly describe what we know and what we do not know about Zika virus.

2. What has been done and what should be done to prevent Zika virus epidemic in US and world-wide?

1. The risk of acquiring disease is measured by the

a. Incidence rate

b. Incidence rate times the average duration of the disease

c. Incidence rate divided by the prevalence rate

d. Prevalence rate

e. Prevalence rate times the average duration of the disease

2. The strength of an association between a factor and a disease is best measure by .

a. Incubation rate

b. Incidence of the disease in the total population

c. Prevalence of the factor

d. Attributable risk

e. Relative risk

3. Case fatality rate for a given disease refers to

a. The crude mortality rate per 100,000 population

b. Cause-specific mortality rate due to the disease

c. A fatal outcome of any disease

d. The percentage of deaths among cases of the disease

e. The proportion of deaths due to the disease among all deaths from all causes

a. Cross-sectional study

b. Case-control study

c. Cohort study

d. Clinical trial

e. Experiment

5. Which of the following statements describes the major advantages of a randomized clinical trial?

a. It avoids observer bias

b. It lends itself to ethical justification

c. It yields results replicable in other patients

d. It rules out self-selection of participants to the different treatment groups

d. It enrolls representative patients

a. Correct b.

Incorrect because of failure to distinguish between incidence and prevalence

c. Incorrect because a proportionate ratio is used when a rate is required to support the inference

d. Incorrect because a failure to recognize a possible cohort phenomenon

e. Incorrect because there is no control or comparison group.

7. An investigator determines the correlation coefficient between triglyceride levels and degree of atherosclerosis in sampled blood vessels to be +1.67. On the basis of this you would conclude that:

a. Triglyceride level is a good predictor of atherosclerosis

b. Triglyceride level is not a good predictor of atherosclerosis

c. High triglyceride levels cause atherosclerosis

d. Atherosclerosis cause high triglyceride levels

e. The investigator has incorrectly determined the correlation coefficient

a. The percent of all negative tests that have false-negative results is lower in population A than in population B.

b. Specificity is lower in population A than in population B.

c. Reliability is higher in population A than in population B.

d. The percent of all positive tests that have false-positive results is lower in population A than in population B.

e. Specificity is higher in population A than in population B.

9. Serum cholesterol levels are obtained for four healthy men. The probability that all will fall below the 10th percentile of the distribution of cholesterol for healthy males is:

a. 0.4

b. 1 â (0.1)4

c. (0.1)4

d. (0.9)4

e. Cannot be determined from these data

10. In a diabetes screening program, the screening level for a positive blood sugar level in test 1 is set at 160 mg/dl, and in test 2 at 130 mg/dl. The sensitivity is:

a. Greater in test 1

b. Greater in test 2

c. Equal in test 1 and 2

d. Dependent on the size of the population being evaluated

KP290 Chapter Notes - Chapter 6: Ecological Fallacy, Digital Camera, Randomized Controlled Trial

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