7. RESPONSE WEIGHTING

We estimate the population for each stratum as follows:
Population@s=Eligibles@s/(Eligibles@s+Ineligibles@s)Frame@s
where: 
    Population@s is the population in stratum s

    Eligibles@s is the number of eligible respondents in stratum s

    Ineligibles@s is number of institutions in stratum s that were
    determined to be ineligible

    Frame@s is the number of records in the sampling frame in stratum s
Ineligibles@s includes the records that IMS drew from the sampling frame and discarded from the sample, and the non-respondents that IMS determined to be ineligible based on telephone follow-up, as well as the respondents that we classified as ineligible based on their responses. As described in Section, IMS needed to draw 1,298 records from the sampling frame to obtain 45 apparent minority museums. We therefore estimate that 45/1,298 (approximately 3%) of the sampling frame are apparent minority museums, which results in: 
      Frame(Apparent Minority) =  404

      Frame(Others) = 11,250.
Our population estimates assume that sample members whose eligibility could not be determined are eligible in the same proportion as sample members whose eligibility was determined. For the Apparent Minority stratum, 69% of the sample could have their eligibility determined, and 84% for the Others stratum, so the assumption seems reasonable. We computed a response weight for each stratum as the ratio of estimated population to eligible responses. Table shows the population estimates and response weights. 
          TABLE :  WEIGHTING OF ELIGIBLE RESPONSES, BY STRATUM

                               Apparent
                               minority    Other

Eligible responses                   20      313
Estimated population                261    8,673
Weight                            13.05    27.71

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