Q: Does a post-hoc analysis study mean that it is a systematic review?
Hmm, I can see why that may be a consideration – because, at a very broad level, both involve looking back at data. But no, they are not the same.
A post-hoc analysis is, as the name suggests, an analysis or study done after the experiment. This typically happens when the experiment does not yield the expected results. The researcher then looks at the data they have obtained and sees whether it leads to some other insight or information. You may learn more about post-hoc studies here:
- What are post-hoc analyses?
- In the Jiboye article, what prompted the researcher to conduct a post-hoc study?
A systematic review is a form of secondary research. It is a detailed, comprehensive review of existing literature around a very specific question. Before starting off on a systematic review, you typically need to register your search protocol, the strategy you will be using to search for and to study related papers. You may learn more about systematic reviews here:
- A young researcher's guide to a systematic review
- Secondary research – the basics of narrative reviews, systematic reviews, and meta-analysis
So, the differences between the two would be:
- For a post-hoc study, you start with the data you have and analyze that, possibly getting a research question out of that, which can lead to a subsequent study. For a systematic review, you need to start with a question, basis which you will look at existing studies in the field.
- You need a search protocol before starting a systematic review. You don’t, for a post-hoc study, but if the analysis leads to you to thinking of a clinical trial (based on your field), you will then of course, need to register your trial protocol.
Hope that helps. And in case you are working on one or the other, all the best for your study! :-)