Immunization of Schoolchildren. In the article, "Reasons for Non - uptake of Measles, Mumps, and Rubella Catch Up Immunisation in a Measles Epidemic and Side Effects of the Vaccine" (British Medical Journal,Vol. 310, pp. 1629-1632), R. Roberts et al . discussed a follow-up survey to examine why almost 10,000 children, ages 11-15, whose records showed no previous immunization were not immunized. In the survey, 10 of the 46 schools participating in the immunization campaign were randomly chosen and then the parents of all the nonimmunized children at the 10 selected schools were sent a questionnaire. What type of sampling design was used by these authors in their survey? Explain your answer.

The given statement is:

In the article, "Reasons for Non - uptake of Measles, Mumps, and Rubella Catch Up Immunisation in a Measles Epidemic and Side Effects of the Vaccine", R. Roberts et al . discussed a follow-up survey to examine why almost 10,000 children, ages 11-15, whose records showed no previous immunization were not immunized. In the survey, 10 of the 46 schools participating in the immunization campaign were randomly chosen and then the parents of all the nonimmunized children at the 10 selected schools were sent a questionnaire.

In this given study, the researchers hope to learn why nearly all youngsters aged 11 to 15 years old were not inoculated, according to the results of the survey.

Ten schools were chosen at random among the 46 that took part in the immunization campaign. A questionnaire was then distributed to all non-immunized children at ten schools that were chosen at random. The population consists of 1285 scholarly journals in the social and behavioral sciences that are grouped into clusters.

As a result, the sampling strategy is cluster sampling.