Split-half. The data collected in the research is split in half and compared with one another. If both halves match/are very similar there is high internal reliability.
Test-retest. Participants complete the same test/ questionnaire under the same conditions but on a different occasion. If this set of results is the same as the first set there is high external reliability.
Two or more researchers work together and both observe behaviours. This can be subjective and make finding bias as people have different methods of research/find different things important.
