define mailing methods.write points of suitability, merits and demerits
Answers
The sources of data can be classified into two types: statistical and non-statistical. Statistical sources refer to data that is gathered for some official purposes, incorporate censuses, and officially administered surveys. Non-statistical sources refer to the collection of data for other administrative purposes or for the private sector.
Answer:
This method is useful when the field of investigation is vast and the respondents are scattered over a wide area.
This is the most economical method in terms of money and manpower.
It is free from the bias of the interviewer.
Respondents have adequate time to give will thought out answers.
Large samples can be made use of and thus the results can be made more dependable and reliable.
Respondents, who are not easily approachable, can also be reached conveniently.
Uniformity in the data collection can be made.