Sample size calculation. For the measurement of iodine status, a
subsample of school-aged children [SAC (6–11 y)] and women of
reproductive age (15–49 y) was included. No data had been previously
collected on iodine status in Somalia, so a formal sample size calculation
was not possible. On the basis of previous survey experience, a target
sample size of 300 participants was selected for the measurement of
urinary iodine concentration (UIC) in each population group in each of
the 3 strata, for a total of 1800. The sample size required per cluster was
then determined by dividing the strata sample into the number of clusters
(35 clusters). No sample size calculation was performed for the
assessment of goiter, and all women between 15 and 49 y of age and
children aged 6–11 y in all surveyed households were included.