Strategies to improve response rates; Advance notification, relevance of content, Respondent-friendly questionnaire, endorsement, follow-up requests, incentives, non-monetary incentives, confidentiality and privacy.
Sampling bias, occurs when some members of a population are systematically more likely to be selected in a sample than others.
Social desirability bias, the tendency of some respondents to report an answer in a way they deem to be more socially acceptable than would be their true answer.
Recall bias, a systematic error caused by differences in the accuracy or completeness of the recollections retrieved by study particiapants regarding events or experiences from the past.
Common Method bias, the amount of spurious covariance shared between independent and dependent variables that are measured at the same point in time.