A screening examination was performed on 250 persons for Factor X, which is found in disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained previously. The results are charted below:
A new blood test has been developed to screen for disease Z. Researchers establish 50 units as a 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?
A screening examination was performed on 250 persons for Factor X, which is found in disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained previously. The results are charted below:
True or False? It is possible for a measure to be valid but unreliable.
True or False? Specificity refers to the ability of a screening test to identify only nondiseased individuals who actually do not have the disease.
A test that determines whether disease is actually present is a:
Sensitivity and specificity of a screening test refer to its:
A new screening test for Lyme disease is developed for use in the general population. The sensitivity and specificity of the new test are 60% and 70%, respectively. Three hundred people are screened at a clinic during the first year the new test is implemented. Assume the true prevalence of Lyme disease among clinic attendees is 10%. Calculate the following value. The predictive value of a positive test is:
A new screening test for Lyme disease is developed for use in the general population. The sensitivity and specificity of the new test are 60% and 70%, respectively. Three hundred people are screened at a clinic during the first year the new test is implemented. Assume the true prevalence of Lyme disease among clinic attendees is 10%. Calculate the following value The number of false positives is:
True or False? Validity is the ability of a measuring instrument to give a true measure.
True or False? Reliability refers to the ability of a measuring instrument to give consistent results on repeated trials, regardless of its accuracy.
True or False? Sensitivity refers to the ability of a screening test to correctly identify all screened individuals who have a disease.
True or False? If a disease is fatal, virulence can be measured by the case fatality rate.
You have just finished administering a food/drink questionnaire to ill and non-ill participants in a Minnesota summer picnic party. The ill individuals developed moderate to severe diarrhea 16 to 46 hours after the picnic. Six persons experienced vomiting. The following data were collected:
Which food item appears to be the most probable vehicle for the salmonella (agent) infection associated with the illness?
Host factors in the causation of disease include:
True or False? The reservoir for Q fever is infected livestock, e.g., cattle, sheep, or goats.
True or False? Herd immunity must be 100% to confer protection to a group.
Which of the following examples involves indirect transmission of disease?
An important point about the agent-host-environment model (the epidemiologic triangle) of epidemiologic investigation is that:
True or False? A secondary attack rate is used to show the spread of disease in a household.
True or False? Physical environmental factors in the natural history of disease include weather, temperature, and biologic components.
True or False? Administration of immune globulin confers passive immunity.
True or False? Eradication of smallpox was successful because of a program to immunize its primary reservoir, the green monkey in central Africa.
True or False? Lyme disease is an example of a disease transmitted by arthropod vectors.
An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty- five people had fever and diarrhea, five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. The attack rate of salmonellosis was: