[Application of Monte Carlo sampling method in iodized salt monitoring]

To explore a sampling method which could reflect iodine deficiency disorders (IDD) status at provincial level and discover risk areas with non-iodized salt problem.

Baseline data of Iodized salt from Gansu and Fujian provinces were analyzed with Monte Carlo method both at county and prefecture levels respectively. True positive rate and false positive rate were also calculated.

With data from 7 - 8 villages or 4 - 5 townships counties at risk could be discovered. The true positive rate was around 80% and false positive rate was around 20%. At prefecture level, when randomly selecting and checking 3 counties, the samples would satisfy the discovery of all the risk areas with non-iodized salt problem.

We suggested that the sampling method of iodized salt investigation in national IDD surveillance as follows: to randomly choose 3 counties at each prefecture, 4 townships at each county, 2 villages at each township and 10 salt samples by household survey. The coverage rate of iodized salt in a province could be calculated by post-weighted method with population number.