Planned observation: Observation in an artificial setting set up by the researcher.
Camouflaged observation: the respondent is unaware that he/she is being observed, the main advantage is that the respondent does not change his/her behavior due to the observation technique, which is more realistic.
Non-disguised observation: the respondent is aware that they are being observed. The main advantage is that richer data can be collected, e.g., additional data can be obtained about the characteristics of the respondent (e.g., demographics, purchasing habits, etc., can be obtained later through questioning)
Direct Observation: Direct observation of the actual phenomenon or behavior.
Indirect observation: looking at the results of a phenomenon or behavior, such as observing some hidden or past behavior. Mainly includes archival records and physical traces.
Work observation: human observation, without the use of other equipment observation methods.