Secondary data includes:
- official stats
- TV documentaries
It's quickly collectable and easily comparable.
It gives info about the past therefore the past and the present can be compared.
No need to worry about informed consent (making people awared that they are a part of a research or study)
- the data might be unreliable or invalid
- official stats might be biased
- sometimes the area you are particularly interested has not been studies before
- the original researcher's values might affect the way the data is presented - possiblity of misinterpretations is high