THE EFFECT OF CLUSTERING ON COSTS AND SAMPLING ERRORS OF RANDOM SAMPLES (REPRINTED FROM JOURNAL-OF-THE-MARKET-RESEARCH-SOCIETY, VOL 19, 1977)

This paper first reviews briefly the theory associated with clustering used in the design of random samples. A further section deals with so me particular intra-class correlation coefficients calculated from var ious town surveys, where different degrees of clustering were employed . These calculated coefficients are summarised and an attempt made to assess their effect when used on national samples. Costs for such nati onal studies are estimated and some compromise sampling solutions sugg ested. The effect of changing the number of interviews in each cluster is investigated.