st: Sampling question: whether to stratify

["Ilian, Henry (ACS)" <Henry.Ilian@dfa.state.ny.us>]

We are conducting a record-reading assessment of casework practice in a large child protective service agency. We have been asked to look separately at each geographic unit of the agency, which results in a very small sample of 27 for each unit (the most that can be handled in the time allotted by the available readers). Eventually all units will be sampled, and the sample size for the agency as a whole will be large enough for an agency-wide assessment. There are two types of cases we are looking at: those that do and those that do not have sufficient support for the allegation of child abuse or neglect which brought them to the agency's attention. The sample is stratified to get a representation of each. Additionally about half of the cases, agency-wide, are initiated by calls that come in outside of business hours. These calls are handled differently, and we have been asked to do a separate assessment of these cases.

My question is, given the large proportion of cases in the outside of business hours group, is it necessary to stratify the sample further or can we expect that a sufficient sample of these cases will be generated as part of the overall sample?

Thanks,

Henry

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