What is Mail questionnaires?

What is Mail questionnaires?

While conducting research, we need to use any tool to collect data from our respondent. Questionnaire is a tool, used for data collection. When we send these questionnaires to the respondent via mail, we call it ‘mail questionnaire’. There are so many reasons behind the use of mail questionnaire, may be respondent are not accessible, far apart from the place where is conducting, or there may be some other reasons to use ‘mail questionnaire’.