Primary and secondary data

What is the difference between primary data and secondary data? Suppose that an author has obtained primary data from ‘the field’ and published findings from an analysis of that data. If the author’s primary data is accessible you can use it yourself to carry out your own analysis and publish your own findings, which might differ from those of the original author. For you, the data is secondary data. Wikipedia describes this well. Suppose, however, that you take the author’s document and, instead of using the underlying raw data from which the document was created, you carry out a content analysis of the document itself. For example you might analyse a project feasibility study to evaluate its compliance with standard project management methodology. Your content analysis will produce primary data. There are, of course, other ways of obtaining primary data. For example you might interview people who worked in the organisations associated with the feasibility study. But the point is that you don’t have to carry out surveys, interviews and the like in order to obtain primary data.