Coronavirus disease (COVID-19) technical guidance by WHO Investigation protocol for COVID-19 | Page 11

4
Statistical analyses
4.1 Sample size
The figure below provides estimates of margin of error as a function of seroprevalence for 100, 200
and 300 samples. For a given seroprevalence rate p and sample size N, the expected margin of error
corresponds to the expected width of the 95% confidence interval associated with the point
estimate of p obtained using binomial likelihood.
4.2 Epidemiological parameters
The table below provides an overview of the epidemiological parameters that can be measured as
part of this investigation.
Parameter Definition
(in bracket: “simplified”
expression of it)
Age-specific attack
rate The proportion of
individuals per age strata
who show seropositivity for
COVID-19 virus infection
Age-specific
cumulative incidence The proportion of
individuals per age strata
who show seropositivity for
virus infection
Form and questions
where to get the data
to calculate the
parameters concerned
Comments, limitations
*Proportion should be
adjusted for any
difference in the age
stratification of the
participants and the
overall population
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