USMLE Forum Archives - USMLE Step 3 - Biostat
Biostat
harry206 - 05-31-09 08:56
Two separate tests for the detection of anthrax exposure have recently been developed, a general screening test and a confirmatory diagnostic test. The screening test is used in the general population, while the diagnostic test is used to confirm suspected cases already identified by other means. Non-physician field personnel administer the screening test, while physicians or technicians under physician supervision administer the diagnostic test. The screening test is much cheaper than the diagnostic test, costing only 1/10 as much. Although both have the same level of sensitivity, over the course of their use, the diagnostic test is discovered to have a substantially higher positive predictive value. This difference between the two tests is most likely accounted for by the
harry206 - 05-31-09 08:56
Two separate tests for the detection of anthrax exposure have recently been developed, a general screening test and a confirmatory diagnostic test. The screening test is used in the general population, while the diagnostic test is used to confirm suspected cases already identified by other means. Non-physician field personnel administer the screening test, while physicians or technicians under physician supervision administer the diagnostic test. The screening test is much cheaper than the diagnostic test, costing only 1/10 as much. Although both have the same level of sensitivity, over the course of their use, the diagnostic test is discovered to have a substantially higher positive predictive value. This difference between the two tests is most likely accounted for by the
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#11
Re: Biostat conym5 - 04-11-10 08:34 sample size calculations for studies designed to estimate disease prevalence that uses a hierarchical model for estimating the proportion of infected clusters..
#15
Re: Biostat babbu5508 - 08-31-10 00:49 My answer is: d.
positive predictive value depends on the prevalence of the disease within within the sample tested...........
#17
Re: Biostat babbu5508 - 09-30-10 01:38 PPV is the most important measure of a diagnostic method as it reflects the probability that a positive test reflects the underlying condition being tested for. Its value does however depend on the prevalence of the disease, which may vary.
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