निम्नलिखित में से कौन सी वह वैचारिक संरचना है जिसके भीतर शोध संचालित किया जाता है और जो डेटा के संग्रह, माप और विश्लेषण के लिए खाका (blueprint) तैयार करती है?

Which of the following statements are correct regarding the core elements of research design execution? A. Identifying the universe and unit of study includes specifying the attributes of the universe and the focus group. B. A pilot study is a preliminary investigation conducted to test and refine research methods before the main research begins. C. Sampling involves selecting a representative section of the universe to maximize sampling error for efficient analysis. D. Post data collection, the analysis phase includes data classification, coding, and tabulating while ensuring ethical representation. Choose the most appropriate answer from the options given below:

In standard evaluation research methodology, how many main stages are broadly identified in conducting an ex-post facto evaluation study?