Primary and secondary reasearch pros and cons

Primary research

Pros
Directly applicable to project.
More valid and less likely to be a correlation.
You can freely choose the method and focus of research.

Cons
Can be biased.
Can be expensive.
Possible risks e.g. doing an interview with dangerous individuals.
Time consuming.

Secondary research

Pros
Cheap.
You can learn from other people's mistakes and carry out your own primary research more effectively.
You can access a range of perspectives.
No risk.
Less time consuming than primary research.

Cons
Secondary research can be biased.
Secondary research will never be totally applicable to your project because your project is new and secondary research is old. as a result it can be used to support primary research but often not take it's place since the secondary research could be loosely related.
Primary research gives a project more credibility.