The group being observed may not realise that the observer is not really 'one of them'
The researcher is able to build a rapport with the participants, meaning the participants are more likely to have open conversations and act in a natural way
The researcher can become too involved with the participants and the interpretation of their behaviour becomes biased as they only see it from the participants' point of view
There are ethical considerations with this type of observation such as deception and right to withdraw because the participants may not know that they are being observed, despite the researcher's participation
The researcher is more likely to remain objective whilst observing and recording the participants' behaviour
The researcher is not able to build rapport with the participants and so they are less likely to open up completely or enough to show the full natural behaviours