The techniques of data collection are: Observation is a regulated perception of facts and circumstances with a definite purpose in view 

There are two types of observation on the basis of different criteria: 

1. Controlled and Uncontrolled observation: Controlled observation implies the use of various tools and instruments to control one or more variable. It usually takes place in a laboratory. Uncontrolled observation is also called unaided observation because it is made in the natural environment without exercising any controls on the phenomena observed.

2. Participant and Non-Participant Observation: The Participant observation method focus on observer or researcher participants in the social phenomena under study. Whereas in Non-participant observation or researcher does not participate, is a loaf and observes the life and activities of the group in a passive manner.

Merits of participant Observation 

• It is possible to observe the natural behavior of the group because the observer is not stranger. 
• It is possible to gather quantitatively more and quantitatively better information. 
• It is possible to get better insights into the phenomena because the observer is an insider. 
• It is possible to observe secrete behavior. 

Demerits. 

• There is a danger objectives because of emotional attachment and over-involment or ego- satisfaction 
• Some phenomena cannot be observed through participation. For instance, an observer cannot become a criminal. Merits of Non-Participant Observation
• It is possible to retain a high level of objectivity. 
• A non-participant observer is able to collect considerable information because of his open role as an observer and his eagerness to learn.

Demerits 

• It is not possible to get information on many aspects of life and activities because observation is limited to formal occasions and organizations. 
• It is not possible to gain insights into many aspects of behavior because the observer is an outsider.

Merits and limitation of Observation Merits

• It is possible to record behavior as it occurs, without any distortions. This gives highly qualitative data. 
• Observation is a flexible method of data collection 
• It is independent of people’s willingness to report.

Limitations 

• Data.collected through observation cannot be quantified 
• There is a danger of bias, especially hidden bias. 
• Observation cannot be used to study private behavior 
• Observation is limited by the duration of the event.

Interview 

The very term implies “Interviewing is an interactional process, it is a mutual view of each other. Structured Interview : has predetermined questions and standard techniques. The number of questions is also fixed. In this method of interview, number and nature of questions, order of asking them, wording of questions, recording system and everything in the interview process is standardized.

Merits of structured Interview:

• It provides safe basis for the generalization , 
• In this method, interview’s bias can be restricted 
• It is more methodical and easy to administer.

Demerits. 

• The rigid and mechanical process, sometimes defeat the purpose of interview. It lacks the flexible nature and personal touch in interview 
• In this method, there is a possibility that substances of interview obtain less importance than formal process and set up.

Unstructured (Oral) Interview: It is not rigid type of interview. In this method, there is flexibility in the entire process of interview. The interview has greater freedom to choose the form depending on situations. The flexibility nature of interview allows the interview to ask number, sequence, and method of questions according to requirements of situations.

Merits of Unstructured Interview 

• The informal nature of interview creates a congenial atmosphere for effective communication. 
• In a highly society of India, the formal set up interview imposes serve limitations on interview. Unstructured interview is the only remedy for this problem.

Demerits of Unstructured Interview 

• The informal nature of interview provides respondents to answer differently, this is difficult in analysis of data. 
• To administer this type of interview, well trained and skilled persons are required. 
• The more number of personal bias and prejudices may be the part of this method.

Merits of Interview method 

• It is possible to obtain highly reliable information and in depth knowledge 
• It is possible to obtain information about the past and also about future plans in a detailed manner. 
• There is a high rate of response 
• Interview method can be used with all types of persons.

Demerits of Interview method 

• There is a possibility of misleading information being given by the interview 
• There can be defects due to the interview who may not be the best person to give information
• There can be defects due to the bias or prejudice of the interview himself, interview is a- difficult skill and needs training 
• It is a costly and time-consuming method.