An interview is the other main type of survey. They consist of an interviewer asking the participant (the interviewee) to answer a series of questions in a face-to-face verbal situation. Having an interview allows both the interviewer and the interviewee to expand on, or clarify the questions. There are three main types of interview:

  1. a structured interview follows a set format, where a questionnaire has been set by an individual and those questions are to be asked of the participant – some clarification on the questions is possible
  2. semi-structured interview consists of a series of set questions, but the interviewer is able to probe the participant into expanding on their answers when necessary, and can also add in a few extra questions to obtain more information
  3. an unstructured interview follows no set format, so the questions are not predesigned – this allows the interviewer to structure the interview entirely around the participant’s answers

The data obtained from an interview is essentially all qualitative. There might be a certain number of dichotomies in an interview, but generally the questions are open-ended.

An interviewer is able to make notes throughout the interview, but a preferred method of recording is to use, for example, a dictaphone or video camera, so a hard copy of the interview is permanently available for the researcher’s use. Either way, the notes or recordings must be transcribed later on – this is, writing them out in full so that the interview can be properly analysed, linking back to your aims and hypotheses. This is time-consuming but is a crutial part of the interview process.

An interview, among any other form of data collection, has to be ethical, and these are some of the steps a researcher has to follow to make sure it is:

  • the respondents must see the interview schedule before the interview begins, so that they know what the interview is regarding and are prepared to respond to the questions asked
  • the respondents must know about and agree to the chosen method(s) of recording the interview
  • after the interview has taken place and it has been transcribed by the researcher, the respondent must see a copy of the transcript to confirm that is what was said or what happened


As with any other method of research, an interview has its fair share of bias. Like in a questionnaire, there is room for the methods of “lying” such as social desirability and response bias. But also, with an interview, the researcher themselves is able to affect the answers from the interviewee. They can do this in the interview by using facial expressions to mentally ‘judge’ the respondent; and they can do it outside of the interview by interpreting the results using their own views and judgements.

The term subjectivity refers to the idea of results analysis being affected by the input of the researcher. This means that they cannot be directly verified by someone outside of the research team. Whereas objectivity means that there is no bias affecting the result – this means that the researcher has not included their own judgement and views in the data. An objective study has findings which are easily verifiable by somebody who is outside of the study team. All scientific studies should be objective.

Interviews can be objective by ensuring that the researcher is not affected by whether they like, or agree, with the interviewee. A full transcript should be produced so the researcher cannot choose what to include. Also, they should have one other researcher look at the results. An interview which is not objective gives findings which are not useful.


Some of the strengths and weaknesses of interview are outlined below:

  • The interviewer is able to explain what the question wants, and can explore further into their opinions by asking further questions, whereas a questionnaire is limited to the questions set
  • Contain in-depth and detailed data is produced which is usually valid – the respondents can talk in their own words and are not restricted – because the data is “real life” and “true” it is likely to be valid
  • An interviewer can find it hard not to influence the answers of the respondent, based on how they ask questions or where they put emphasis on, e.g. by asking “You are not prejudiced, are you?”
  • Interviewees may respond differently to different interviewers, for example, giving different answers to a man or woman interviewer (researcher bias)
  • The researcher can put their own interpretation into the data analysis and can quickly form themes in their mind which they analyse all data to


We all know what they are and have all filled lots of them in.  A questionnaire is essentially a list of written questions that is able to gather lots of relevant information relatively quickly and cheaply.

The biggest problem is wording of the questions.  Again there is the issue of ‘open’ or ‘closed’, but more importantly, as in eyewitness testing, there is the issue of leading questions.  These are a favourite of politicians or of newspapers who want to find support or criticism of a particular issue.  For example imagine you wanted to find out if people wanted more money spent on the NHS, a relatively neutral question might be:

‘Should more money be spent on the NHS?’
A biased newspaper wanting a ‘yes’ response might get their pollsters to ask:
‘Should extra money be provided to the NHS to take care of Britain’s sick and elderly?’

It is always a good idea to test your questionnaire in a pilot study first to make sure it doesn’t take hours to complete and that participants understand the questions.  Feedback like this may provide ideas for follow up questions to be asked in the real study.


  • Lots of people can be tested quickly, as the experimenter only needs to send or hand them out. This allows for greater generalisation to the overall population
  • Data can often be analysed easily, as often closed questions are used, leading to quantitative data.
  • However, lots of questionnaires will not be returned!
  • People may lie on the questionnaire.  Even in anonymous questionnaires this may be an issue.  Lie questions may be included, e.g. in Eysenck’s Personality Questionnaire (EPQ).
  • With closed questions there may not be a suitable answer to adequately express a participant’s response. They may therefore be forced to check a box that does not necessarily reflect their view point. This can lead to lower internal validity.