This document discusses different methods for collecting primary and secondary data. Primary data collection involves directly gathering new data through surveys, interviews, or experiments. It may be costly and time-intensive but allows customization. Secondary data uses existing data that was previously collected, which can save time and money but may have limitations like being outdated. Proper data collection requires defining the research question and population first to determine the appropriate method and variables to use. Common primary methods are experiments, telephone/written surveys, and interviews. Potential biases must be considered like nonresponse, selection, and observer bias.