Direct observation is especially useful when job consist mainly of observable physical activities – assembly-line worker and accounting clerk are examples. On the other hand, observation is usually not appropriate when the job entails a lot of mental activity. (Lawyer design engineer).
Nor is it useful if the employee only occasionally engages in important activities, such as a nurse who handles emergencies. And reactivity – the worker’s changing what he or she normally does because you are watching – can also be a problem. Managers often use direct observation and interviewing together. One approach is to observe the worker on the job during a complete work cycle. (The cycle is the time it takes to complete the job, it could be a minute for an assemblyline worker or an hour, a day, or longer for complex jobs). Here you take notes of all the job activities.
Then, after accumulating as much information as possible, you interview the worker. Ask the person to clarify points not understand and to explain what other activities he or she performs that you didn’t observe. You can also observe and interview simultaneously asking questions while the worker performs his or her job.