This document provides an overview of different approaches to data sampling, collection, and testing. It discusses various units of measurement that can be used and describes structured, semi-structured, and mixed methods for data collection. Structured approaches use close-ended tools like surveys to collect quantifiable data, while semi-structured use open-ended questions in interviews and discussions to gather qualitative insights. Mixed methods combine approaches. The document provides examples of when each approach would be most applicable and addresses common questions about differences between methods.