<prompt> WHO immunization evaluation coverage survey is normally done in what age group?0-12 months6-12 months12-23 months9-12 months  <response>: Ans. is c i.e., 12-23 months WHO used 30 x 7 technique total 210 children for cluster sampling in which there are 30 clusters, each containing 7 childrenwho are 12 - 23 months old and are completely immunized for primary immunization till measles vaccine at 9 month. 