Both the p-value and the reported 95% confidence intervals were adjusted for the multistage stratified cluster sample
design of the study.
Here we report the incidence rate of leprosy in this multistage random cluster sample
from the general population over a 6-year observation period and describe the main characteristics of the patients found.
Even for a small ICC of 0.006 and an average of 200 student respondents per school, the required sample size to achieve the same power for a cluster sample
is more than double (2.2 times) that of a simple random sample.
The margin of error reflects the influence of using a multi-stage cluster sample
and data weighting.
A two-stage stratified cluster sample
design was used (Joncas, 2008); schools were selected during the first stage of sampling and then classrooms within schools were sampled during the second stage.
Respondents were randomly selected from a cluster sample
provided by Survey Sampling International.
(11) Gilbert Burnham, Riyadh Lafta, Shannon Doocy et al., "Mortality After the 2003 Invasion of Iraq: A Cross-Sectional Cluster Sample
Survey," The Lancet, October 21, 2006, 368 (9545), pp.
Researchers at Johns Hopkins released a massive, rigorous cluster sample
survey of Iraqi casualties in October, which found, between 2003 and 2006, an estimated 654,965 "excess deaths"--that is, deaths above and beyond the country's prewar mortality rate.
The survey used a three-stage cluster sample
design to obtain cross-sectional data representative of the nation's high school students.
Using this method, in addition to a cluster sample
counting technique, we conducted exit count surveys at a reasonable cost, and we obtained statistical confidence values.
A two-stage cluster sample
was used to select a representative sample of 97 schools.
A cross-sectional survey of a cluster sample
of primary care patients in California and Canada revealed patients' requests for medicines are a powerful influence on prescribing decisions.