HSC 404, Final Exam Questions and Correct Answers, With Complete Solution, Updated 2024.

HSC 404, Final Exam Questions and Correct Answers, With Complete Solution, Updated 2024. The population etiologic fraction is a measure of the proportion of the disease rate in a population attributable to the exposure of interest. This measure of effect is influenced by: -the relative risk of the disease in exposed individuals versus unexposed individuals AND -the prevalence of the exposure in the population If it is accepted than an observed association is a causal one, an estimate of the impact that a successful preventative program might have, can be derived from: attributable risk When assessing a positive relationship between alcohol consumption and oral cancer using a case-control study, increasing the sample size of the study will result in: -a lower p value -a greater odds ratio -a smaller 95% confidence interval -a higher disease prevalence -none of the above An attributable-risk percent of 80% was calculated for the association between smoking and lung cancer death. The best interpretation of this statistic would be: Of those dying of lung cancer who smoke, 80% of those deaths are attributed to their smoking, assuming a causal association exists. Several studies have found that approximately 85% of cases of lung cancer are due to cigarette smoking. This is an example of: attributable risk Selection bias is most likely to occur in: both retrospective cohort studies and case control studies Recall bias is most likely to occur in: case control studies In a study to determine the incidence of chronic disease, 150 people were examined at the end of a three-year period. Twelve cases were found, giving a cumulative risk of 8%. Fifty other members of the initial cohort could not be examined; 20 of these 50 could not be examined because they died. Which source of bias may have affected the study? selection bias: survival bias You are investigating the role of physical activity in heart disease and suggest that physical activity protects against having a heart attack. While presenting these data to your colleagues, someone asks if you could have thought about confounders such as factor X. This factor X could have confounded your interpretation of the data if it: is a factor associated with physical activity and heart disease The strategy which is NOT aimed at reducing selection bias is: Standardized protocol for structured interviews Which is NOT a method for controlling the effects of confounding in epidemiological studies? Blinding The purpose of a double-blind study is to: avoid observer and interviewee bias In a survey which uses lay interviewers to interview one person about his or her health and the health of household members, the sources of error include: -the person with disease has had no symptoms and is not aware of the disease -the respondent provides the information but the interviewer doesn't record it or records it incorrectly -the interviewer doesn't ask the questions that he or she is instructed to ask, or asks them incorrectly -the person has had symptoms and has had medical attention but does not know the name of the disease An epidemiological experiment is performed in which one group is exposed to a suspected factor and the other is not. All individuals with an odd hospital admission number are assigned to the second group. The main purpose of this procedure is to: -improve the likelihood that the two groups will be comparable with regard to know and unknown confounding factors A double-blind study of a vaccine is one in which: Neither observers nor subjects know which subject receives the vaccine and which receives a placebo The degree of agreement among several trained experts refers to: inter-judge reliability A test that determines whether disease is actually present is a: diagnostic test A new blood test has been developed to screen for disease Z. Researchers establish 50 units as cut point above which a test is considered positive and thereby indicative of disease. The test manufacturers determine that the test's sensitivity is unacceptably low. However, the manufacturers are not concerned with the specificity and do not want the cost of the test to rise. How can they improve the sensitivity of the test? lower the cut point below 50 units Dr.s Poke and Jab (2014) conducted an employee health program that used 5 screening tests at the same time to detect diseases among workers. Which type of program is this? multiphasic screening Lead time bias is best described as: an apparently longer survival time among persons identified during a screening program because they were identified at an earlier stage of their disease A new antibody test detects serum antibodies against virus X (sensitivity 99%, specificity 90%). When applied in a group of hospitalized patients diagnosed as having virus X infections, the test is found to have a positive predictive value of 30%. What best explains this difference between the positive predictive values?