What are the important issues to consider when using secondary data? Say you want to conduct a research study that observes people engaged in a generic activity. Rather than record this evidence oneself, would it be wise to try to gather recorded evidence that was part of other research studies? I am asking about gathering raw evidence, to re-analyze for the purposes of a new study, not leveraging/citing data/conclusions in other research studies. For example, if another research study recorded 1000 hours of people doing general enough activities, would I be able to ask the owner of that study to share their recorded evidence with me, so that I might use it for my own analysis?

In other words, what are some of the issues to consider when using secondary data?

If it isn't common, why not? What are the pitfalls of using evidence gathered from other studies, to drive my own research?
Reusing data gathered in previous research works save a lot of time, energy and may be money. However, there are some subtle details you need to keep in mind when using such practices.


Make sure the author providing the data knows what he is talking about.
Make sure the data are valid and genuine.


As I heard from one of my professors, citing results of another author does not mean that you would not be held responsible in case of false/inaccurate results.

Update: Following the comment about raw data I think such data can be trusted, unless proved otherwise. Also, it is better to go for raw data (data sets) used widely thus reducing the chance there would be something terribly wrong with the data.