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| Mailing survey means to deliver investigation questionnaires and correlative information to respondents who need to complete the questionnaire in requirement and resend. There are two methods:the first one , to leave questionnaire forms and introduction to respondents and book a deadline to collect the questionnaire forms which have been completed .the second one, to post questionnaire forms to the fixed samples . The applied extension includes:Low efficiency requirement, complete panel, plenty of investigation content, sensitive survey questions items. |
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