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Question 686
Statistics → Epidemiology
Classification
Question
SSBAQuestion Header
Statistics
Question Stem
A surveillance programme records only patients who are newly diagnosed with a condition during a defined 12-month period. Which epidemiological measure is being determined?
Options
A
Prevalence
B
Specificity
C
Incidence
D
Positive predictive value
E
Reliability
Explanation
Incidence is the number of newly diagnosed cases of a condition occurring over a specified time period. The key distinction from prevalence is that incidence concerns new cases, whereas prevalence measures all current cases within a population at a particular point or defined interval.
Option Validity
A) Prevalence measures existing cases in the population.
B) Specificity evaluates the probability of a negative test in someone without the condition.
D) Positive predictive value concerns the probability of disease following a positive test.
E) Reliability concerns consistency or reproducibility rather than disease occurrence.
Further Reading
Saxena - MRCOG-1 Basic Sciences, Chapter 10: Epidemiology/Statistics, Printed p.287.