what mailing method

 Some surveys can be conducted through the use of mail questionnaire. Under this method, a list of questions pertaining to the enquiry is prepared and sent to various informants by post. The questionnaire contains questions and provide space for answers. A request is made to the informants through a covering letter to fill up questionnaire and send it back within a specified time.
Merits :
1. The merit of this method is that it does not allow the influencing of the respondent by the interviewer.
2. Mailing costs are much lower than the costs of personal visits.
3. It allows the respondents to remain anonymous.
4. It can reach all groups including those whose personal specialization is not possible.
Demerits :
1. This method can be adopted where the informants are literate people.
2. It involves some uncertainty about the response.
3. The informations supplied by the informants may not be correct.