Q: What are the limitations of secondary data collection?
Secondary data is data collected by an individual or group other than the researcher conducting an experiment and that is available before commencing the current experiment. (In contrast, primary data is collected by the individual or group conducting the experiment and obtained as a result of the experiment.) Secondary data, which includes grey or unpublished literature, is typically used for writing the literature review of a paper, for writing review papers, and for providing citations and references in a paper. Secondary data collection has some benefits. It saves time, as the data is already available. Additionally, the data, by and large, is already verified. Also, secondary data is especially helpful in providing insights and directions for new research. For instance, after doing a literature search, you may come across some gaps in the literature, which can lead to identifying a potential topic for research.
However, as you have rightly observed, there are also limitations to secondary data collection. While you may use secondary data as reference, it may not always suit the exact purpose of your study. So, you may need to be cautious if directly using the results of another study for your study. Also, as some secondary data includes unpublished literature, it may not always be verified, not having undergone peer review. Another problem with secondary data could be that bias may have crept in while obtaining the data, which you have no visibility into but that may inadvertently affect your study. For these various reasons, it helps to not always take secondary data at face value, and instead, dig a bit deeper into the purpose and question of the earlier studies to get a broader view of the data.