A lower-than-normal response rate does not necessarily mean that responses are biased.

SMS questionnaires, are only suitable for long questionnaires.

Responses to interviewer-administered questionnaires are recorded by the respondent.

Demographic, data that cannot be collected using questionnaires.

The design stage of a questionnaire is not likely to involve substantial rewriting in order to ensure that the respondent follows instruction and decodes your questions in the way you intended.

Structured interviews, refers to those questionnaires where interviewers physically meet respondents and ask the question face to face.

Internal validity in relation to questionnaires refers to the ability of your questionnaire to measure what you intend it to measure.

Respondents to telephone and face-to-face questionnaires are more likely to answer to please due to their contact with you, although the impact of this can be minimised by good interviewing technique.

For many research projects an understanding of relevant organisations can be achieved through semi-structured interviews.

Researcher-completed questionnaires will usually have a lower response rate than self-completed questionnaires.