patient satisfaction of performance of triage nurse in health centers
This sounds like a good topic, but it needs to be more specific.
If you want help to understand reliability and validity for your research design, I need to know what kind of research design you are using.
If you are using a survey design, you can find some great information by googling this: survey, research design, validity, reliability
The "reliability" is the extent to which you can get the same results by repeating the study over and over.
The "validity" is the extent to which the study measures what it is supposed to measure.
Some more good things to google are below:
participant bias
researcher bias
validity vs. reliability
Good luck!!!