Observation Sampling Technique:

Since it  is usually impossible  to  observe behaviour for extended period of time because of fatigue and boredom  one must plan how and when to make the observalion. The most commonly used techniques are: 

i) Time Sampling Method: This procedure involves the selection of time periods during which the observation will take place. One decides the day into units that are appropriate for observation. The  time frame may be systematically selected  e.g. one can observe intermittently at  10 minutes interval for  8 hours a day  or  intermittent instantaneous observation may be carried  out at 10 minutes interval for 24 hours.  Time  frames can be selected at  random. Here  it  is important that the researcher  uses  some system of signal when the observer should start looking  and when to  stop.Duration of observation should be  decided before hand. 

ii) Event Sampling: When we want to observe an  entire event  in order to give  the subject  the opportunity to perform all of the expected behaviours. The observer selects  integral behaviour  or  event of a pre-specified  type of observation. Researcher either requires  to know the occurrence of event or be  in a position to wait for their occurrence e.g. a researcher observed aseptic practices  in urinary catheterization where  she observed the full procedure against the steps listed under different areas of procedure  e.g. washing  and  drying hands, wearing gloves, etc. Slhe carried out observation  in  surgical ward, surgical O.P.D., casualty department.