This document discusses data types and sources for research. It describes primary and secondary data, with secondary data being information collected previously for other studies. Secondary data sources can help with problem identification, hypothesis design, sampling, and validating primary research findings. Benefits of secondary data include resource and time savings, while drawbacks include potential lack of applicability or accuracy for the current study. The document also outlines internal sources like company records and external sources like government data, and stresses validating the methodology, accuracy, timeliness and cost of using secondary data.