5Brogan D, Flagg E, Deming M, et al. Increasing the accuracy of the expandedprogramme on immunization's cluster survey design [J] . Ann Epidemiol, 1994, 4: 302-311.
6Galvao L, Kaya K.Using lot quality assessment techniques to evaluate quality of data in a community-based health information system [J] .Tropical Doctor, 1994, 24 (4): 149- 151.
7Paul Milligan, Alpha Njie, Steve Bennett. Comparison of two cluster sampling methods for health surveys in developing countries [J] .Int J Epidemiol 2004, 33: 469 - 476.
