Four method of survey:
1. Nature of the Population: The population maybe widely scattered then mail surveys are more appropriate and economic. If the respondents are not adequately eduated than personal interviews will be better. If the potential respondents own telephones and the information is to be gathered in shortest possible time then telephone surveys are the best.
2. Funds at Disposal: The costs of conducting personal interviews are always higher as compared to telephone and mall surveys. Form the cost consideration the mail is judged best. Costs should be more accurately compared against the quality of information obtained by alternative methods.
3. Duration of Survey: Maximum time is required in personal interviews and in mall surveys the researcher has to wait for longer time to get adequate response. Telephone surveys research minimum time and are the best speed wise.
4. Desired Accuracy of Collected Information : Inaccuracies in information are mainly due to respondents and investigators biases. The factors for respondent bias may be.
a. Unwilling to co operate in the interview and giving biased answers consciously.
b. The respondent may not be able to understand the questions and misinterpret the question. These inaccuracies can be checked and minimized considerably in personal interviews.