<prompt> For survey of immunization by WHO age group selected is ?12 - 23 months0 - 6 months6 - 12 months2 - 5 years  <response>: Ans. is a i.e., 12 - 23 months In the Expanded programme on Immunization EPI cluster technique, a simplified cluster sampling method is used. It is based on ranodm selection of 210 children who are 12-23 months of age. These patients are selected in 30 clusters of 7 children each to estimate immunization coverage levels. 