Advantages of Observational Methods:
Observation forms the basis of any scientific enquiry. It is the primary mode of acquiring knowledge about the environment. Through systematic observation, and a process of induction, the investigator forms hypotheses, which are tested later by using experimental methods.
The results obtained through any other scientific methods need to be in conformity with the outcomes of skilled observation. In case of any departure, the processes adopted in the 'other' methods have to be carefully scrutinized and evaluated.
The experimental and other laboratory-based methods study behaviors under artificially controlled conditions. But through observational method, the investigator gets a real picture of the behaviors and the events as they manifest in natural settings. Systematic and unbiased observation can yield a true picture of individual's natural set of behaviors.
Certain phenomena can be accessed and properly understood only through observation. Crowd behavior, social behaviors of the animals, and mother-child interaction at home are some exemplary situations, which can be meaningfully assessed, and understood only through observation.
Disadvantages of Observational Method:
The major problem with observational methods is that the investigator has little control over the situation he is interested to observe. In the natural setting, too many extraneous factors influence the phenomenon. As a result, it is difficult to assess what causes or determines the behaviors of researcher's interest. It is extremely difficult, and sometimes impossible to establish cause-and-effect relationships in our understanding of the behaviors. The observational report in most cases turns out to be descriptions of events rather than explanations for the event that can be used for prediction and control.
In many cases the observer has to wait until the appropriate event takes place. To study crowd behavior, the investigator would have to wait until a crowd is formed in a natural setting. Therefore, some types of observations are time-consuming, and labor-intensive.
Observer-bias is one of the important problems in observational research. The personal philosophy, attitudes, beliefs, convictions, and sometimes the personal interests of the observer are most likely to color his perceptions of the event. His observational report may in part reflect his biases in describing and interpreting the event. Thus, the description may not reflect the true features of an event.
The observer himself, during the course of observation, may be affected by the process itself. His initial neutral disposition may be affected and distorted. The outcome would be a description of the event as personally experienced by the observer. These descriptions would be subjective, and cannot be generalized to other similar situations.
Finally, the presence of the observer may influence the phenomenon itself. In other words, those subjects who are observed may change their activities in the presence of the observer. As a result, the observer would fail to obtain a true picture of subject's behaviors, i.e., those behaviors that would have taken place, if the observer would not have been present. It is always better to supplement the observational record with the findings obtained through other methods.