Pj. Smith et al., Overview of the sampling design and statistical methods used in the National Immunization Survey, AM J PREV M, 20(4), 2001, pp. 17-24
The National Immunization Survey (NIS) is a large federally funded survey d
esigned to estimate vaccination coverage rates for children residing in die
United States aged 19 to 35 months. In 1999, over 8 million telephone call
attempts were made to obtain provider-reported vaccination histories on 22
,521 children in the age range of interest.