<prompt> Sampling method used in assessing immunization status of children under immunization programme is -Systemic samplingStratified samplingGroup samplingCluster sampling  <response>: Ans. is d i.e., Cluster sampling Important facts of cluster random sampling CRSo Cluster sampling is used in India to evaluate immunization coverage.o WHO used 39 x 7 technique total 210 children for cluster sampling in which there are 30 clusters, each containing 7 children who are 12 - 23 months old and are completely immunized for primary immunization till measles vaccine at 9 montho Clusters are heterogenous within themselves but homogeneous with respect to each othero Main objective of cluster sampling is to reduce costs by increasing sampling efficiency; in contrast to stratified sampling where; the main objective is to increase precision.o Cluster sampling is quiet accurate with low error rate of only - 5.o Cluster sampling can also calculate sampling interval.o The main limitation of cluster sampling is that cluster cannot be compared with each other. 