INTERVIEWS

Interviews are usually face-to-face conversations (although they can take place over a telephone or over social media).

What makes an interview different from a questionnaire is that the interviewer is contributing at the same time as the interviewee. This usually takes the form of the interviewer asking questions and the interviewee answering them - but sometimes the interviewee might ask questions or the interviewer might offer instructions, clarifications or responses of their own.

Unstructured interviews are apparently informal chats - but there's still a purpose behind them. Unstructured interviews put the interviewee at ease and produce natural responses (i.e. they are valid) but no two unstructured interviews will be exactly the same (i.e. they are not reliable). The big advantage is that the interviewer can stop and pursue an interesting line of conversation or go back over questions that weren't answered clearly.

Structured interviews have pre-determined questions - they don't sound or feel much like a normal conversation. Structured interviews always feature the same questions in the same order (i.e. they are reliable) but they are stilted and unnatural (i.e. low in validity). The main advantage is that lots of participants can be interviewed this way and their responses easily compared.

Semi-structured interviews contain pre-determined questions but also feature informal chat - they sound and feel more realistic than structured interviews. They aim to get "the best of both worlds" (the validity of unstructured interviews and the reliability of structured interviews) but they are difficult to do: the interviewer has to be well-trained or quite experienced.

Interviews are often recorded (either audio-only or filmed). They can be transcribed (written down) later and analyzed in detail.

Unstructured interviews are not always obvious on who is the interviewer and who is the interviewee.

Structured interviews are where the questions are fixed in advance and only certain responses are allowed (even if you try to talk about something else)

With Semi-structured interviews there are some questions that must be asked, but room for natural conversation as well.

You'll notice that all interviews suffer from researcher effects, that is, the researcher might give directions to some interviewees through tone or body language or else the interviewees might feel hostile towards or intimidated by some researchers.

QUESTIONNAIRES (Surveys)

Questionnaires aren't conducted face-to-face; even if the researcher is present, they don't communicate with the respondent while they're completing the questionnaire (except perhaps to explain the purpose). Questionnaires involve reading the questions followed by a written response - although the writing might be no more than ticking boxes.

Unlike interviews, questionnaires are always structured - the questions have to be written in advance. However, there are different types of question that can be asked:

Open questions allow the respondent to answer in any way they like. The best open questions encourage longer answers and begin with words like "How" and "Why" - questions beginning with "What" and "When" tend to produce limited answers. The advantage is that the respondent doesn't have to feel restricted about how they answer, but it can be very difficult to score or compare the qualitative data you get from open questions.

Closed questions only allow an answer from a list of responses. The simplest type of closed question is a "Yes/No" question. More complicated closed questions can be multiple-choice questions. It's easy to score closed questions as quantitative data, because the researcher knows all the possible answers in advance. The problem is that the respondent might want to give an answer that isn't among the options provided (like "Sometimes" or "It Depends").

There are different types of closed questions:

MULTIPLE CHOICE

This produces nominal level data - you get the frequency that each option was ticked, which you can express as percentages.

RANKED SCALE

This produces interval/ratio level data - you can give each respondent their own score. The classic "on a scale of 1-10" question tends to bunch in the middle (no one chooses 1 or 10) and it doesn't tell you what each number means - just how bad is 1? how great is 10? Some rating scales disguise the scores

LIKERT SCALE

Invented by Rensis Likert (pronounced Lick-hurt), a Likert scale offers a statement (not a question) and the respondent indicates how strongly they agree or disagree. This produces a 1-5 (or 1-7 if you add "Very Strongly...") rating scale, so it can be turned into either nominal or interval/ratio level data.

Some researchers prefer to remove the "Undecided" option - forcing respondents to agree or disagree.

Similar to a Likert scale, this invites respondents to indicate where their attitude falls between two extremes. The middle option scores "0" and placing yourself to the left or right scores -1, -2 or +1, +2, etc. The scoring can be hidden from the respondents. Normally there are several different scales to fill in, expressing different extremes. This can produce nominal level data (the frequency of positive or negative responses) or interval/ratio level data (if every respondent gets a total score)

You can turn a semantic differential scale into a graph by connecting the responses (or the mean or mode of all the responses) with a line.

You will have spotted a limitation of questionnaires: only people who can read and write can complete them. If the questionnaires contain complicated language, you might have to be quite educated to complete.

Advantages of Self-Report Data

One of the primary advantages of self-report data is that it can be easy to obtain. It is also an important way that clinicians diagnose their patients—by asking questions. Those making the self-report are usually familiar with filling out questionnaires.

For research, it is inexpensive and can reach many more test subjects than could be analyzed by observation or other methods. It can be performed relatively quickly, so a researcher can obtain results in days or weeks rather than observing a population over the course of a longer time frame. Self-reports can be made in private and can be anonymized to protect sensitive information and perhaps promote truthful responses.

Disadvantages of Self-Report Data

Collecting information through a self-report has limitations. People are often biased when they report on their own experiences. For example, many individuals are either consciously or unconsciously influenced by "social desirability." That is, they are more likely to report experiences that are considered to be socially acceptable or preferred. In self-report there are some limitations which are discussed below:

i). Honesty: Subjects may make the more socially acceptable answer rather than being truthful.

ii). Introspective ability: The subjects may not be able to assess themselves accurately.

iii). Interpretation of questions: The wording of the questions may be confusing or have different meanings to different subjects.

iv). Rating scales: Rating something yes or no can be too restrictive, but numerical scales also can be inexact and subject to individual inclination to give an extreme or middle response to all questions.

v). Response bias: Questions are subject to all of the biases of what the previous responses were, whether they relate to recent or significant experience and other factors.

vi). Sampling bias: The people who complete the questionnaire are the sort of people who will complete a questionnaire. Are they representative of the population you wish to study?