Primary research involves collecting original data through methods like questionnaires, interviews, experiments and observations. Secondary research summarizes and analyzes existing research, such as previous studies or primary data, rather than collecting new data. Common secondary research methods include systematic reviews and market research, while primary research may inform areas of focus for secondary research.

1. PRIMARY AND SECONDARY RESEARCH
Primary
Primary research consists of the collection of original primary data. It is
often undertaken after the researcher has gained some insight into the
issue by reviewing secondary research or by analyzing previously
collected primary data. It can be accomplished through various
methods, including questionnaires and telephone interviews in market
research, or experiments and direct observations in the physical
sciences, amongst others
Secondary
Secondary research (also known as desk research)involves the summary,
collation and/or synthesis of existing research rather than primary
research, where data is collected from, for example, research subjects
or experiments. The term is widely used in medical research and in
market research. The principal methodology in medical secondary
research is the systematic review, commonly using meta-analytic statistical
techniques, although other methods of synthesis, like realist reviews