Planning observation: the researcher artificially sets the observation environment.
Camouflage observation: the interviewee doesn't know that he is being observed. The main advantage is that the interviewee will not change his behavior because of observing technology, which is more real.
Non-disguised observation: Respondents know that they are being observed. The main advantage is that richer data can be collected, such as additional data about the characteristics of the interviewee (such as demographic data, purchasing habits and other data can be obtained by asking later).
Direct observation: direct observation of actual phenomena or behaviors.
Indirect observation: the result of observing phenomena or behaviors, such as observing some hidden or past behaviors. It mainly includes archival records and physical traces.
Work observation: manual observation, without the help of other equipment.