o record-keeping may be inconsistent
o some of the events may not be familiar to the researcher, and therefore they may not understand what is happening
o if more than one observer is involved, the results may be skewed
o the constant attention and involvement of the researcher is needed.
Moreover, it is necessary that the researcher has an understanding of what is going to be recorded and for what purpose, and so on. It would be helpful to have a form prepared for recording data.