Advantages/Disadvantages - Participant observation

Advantages:
Participants behave as they normally do, so evidence is valid
It takes the viewpoint of the participants rather than the researcher
It can dig deep into social interaction
The researcher is open to new insights (the questions are not fixed in advance)

Disadvantages:
It studies small groups so may not be representative
It cannot be checked or repeated for reliability
It is time-consuming in relation to the amount of data collected
The researcher's presence may change the behaviour of the grouo
The researcher may be biased
If the research is covert there are more potential disadvantages:
It can raise serious ethical issues as there is no consent
The researcher may be at risk
The researcher may not be able to ask the questions they would like to ask, as they may risk uncovering who they actually are