When is it considered acceptable to adopt the one-group posttest-only design?

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It is acceptable when clients’ pre-test status can be collected without a formal assessment. In some special cases, information about the pre-test status can be collected from the documents, such as medical history, social work service records, etc. In other cases, the pre-test status is one of the recruitment criteria, and the evaluators can assume the participants in the program have identical status. The information serves as pre-determined benchmarks in the subsequent evaluation process.