The most important thing in evaluating for relevance to your specific research project is to be clear on what your research question is. What are you trying to find out about your topic?
(1) WHAT IS THE SCOPE (how broad or narrow is it?)
For instance, if your topic is: learning disorders
- and your research question is: What are some common learning disorders in elementary school-aged children?
The following articles are probably too specific and too narrow to be relevant:
However, if your topic is: learning disorders
- and your research question is: What affects the comorbidity (co-occurrance) of different kinds of learning disabilities, and does having family members with more than one type of learning disability affect one's risk of having learning disabilities (and if so, how)?
- then the third article above would be of the right scope.
However, the following sources would be too broad for that question:
(2) WHAT IS THE FOCUS? (Which aspect(s) of the topic does the source address?)
(3) WHEN WAS IT WRITTEN?
If you are looking for the most recent and up-to-date research on treating Alzheimer's disease, a research article from 20 years ago will not be appropriate and relevant.
For many of your research projects, you will be looking for recent materials, but some fields change faster than others.
If you're not sure if a source is relevant
This often happens at the beginning of working on an assignment, and most often the real problem is a lack of clarity about the research topic and question. For tips on choosing and narrowing a topic, see How to Focus My Research Question - or come talk to a librarian!