I know what primary and secondary data collections are, but why must secondary data collection be conducted early in a project and the primary data collection be done later in the project?
2 answers
I have no idea. I always read primary sources first and then found secondary sources, some of which supported whatever angle I ended up taking.
I am not certain we agree on primary and secondary.
If raw data is collected by the researcher, it is primary.
If the raw data was collected by someone other than the author, it is secondary. For instance, using census data to evaluate teen pregnancy is secondary data.
Secondary data often evaluates several sources, and can summarize "findings". In some areas, it can point to valuable holes in data, and areas that need to be explored, once those are established, the search for primary data begins in earnest.
However, bias is bias, and you find it in primary sources and secondary sources, so I would not make a hard rule on which to focus on first.
If raw data is collected by the researcher, it is primary.
If the raw data was collected by someone other than the author, it is secondary. For instance, using census data to evaluate teen pregnancy is secondary data.
Secondary data often evaluates several sources, and can summarize "findings". In some areas, it can point to valuable holes in data, and areas that need to be explored, once those are established, the search for primary data begins in earnest.
However, bias is bias, and you find it in primary sources and secondary sources, so I would not make a hard rule on which to focus on first.