Secondary research involves the summary, collation and/or synthesis of existing research. Secondary research is contrasted with primary research in that primary research involves the generation of data, whereas secondary research uses primary research sources as a source of data for analysis. A notable marker of primary research is the inclusion of a 'methods' section, where the authors describe how the data was generated. Secondary research involves the summary, collation and/or synthesis of existing research. Secondary research is contrasted with primary research in that primary research involves the generation of data, whereas secondary research uses primary research sources as a source of data for analysis. A notable marker of primary research is the inclusion of a 'methods' section, where the authors describe how the data was generated. Common examples of secondary research include textbooks, encyclopedias, news articles, review articles, and meta analyses. When conducting secondary research, authors may draw data from published academic papers, government documents, statistical databases, and historical records. The term is widely used in primary research, legal research and market research. The principal methodology in health secondary research is the systematic review, commonly using meta-analytic statistical techniques, but other methods of synthesis, like realist reviews and meta-narrative reviews, have been developed in recent years. Such secondary research uses the primary research of others typically in the form of research publications and reports.