Interviews and interviewees can be a source of response error. Response error occurs when data reported is not equal to the actual data. Response error can be introduced by interviewer bias, or because the interviewee does not accurately answer the questions; respondents/interviewees may choose to answer inaccurately or they may not possess the knowledge to answer accurately.

Non-response error occurs when participants are unavailable or when the interviewer cannot successfully encourage the intended participant to respond.