‘Original research’. The term primary studyAn investigation of a healthcare problem. There are different types of studies used to answer research questions, for example randomised controlled trials or observational studies. is sometimes used to distinguish it from a secondary study (re-analysis of previously collected dataData is the information collected through research.), meta-analysisThe use of statistical techniques in a systematic review to combine the results of included studies. Sometimes misused as a synonym for systematic reviews, where the review includes a meta-analysis. , and other ways of combining studies.
