A self-report study is a type of survey, questionnaire, or poll in which respondents read the question and select a response by themselves without researcher interference.
A self report is any method which involves asking a participant about their feelings, attitudes, beliefs and so on. Examples of self reports are questionnaires and interviews; self reports are often used as a way of gaining participants responses in observational studies and experiments.

Self-report instudies have validity problems. Patients may exaggerate symptoms in order to make their situation seem worse, or they may under-report the severity or frequency of symptoms in order to minimize their problems.

Questionnaires and interviews

Questionnaires are a type of self report method which consist of a set of questions usually in a highly structured written form.
Questionnaires can contain both open questions and closed questions and participants record their own answers.
Interviews are a type of spoken questionnaire where the interviewer records the responses. Interviews can be structured whereby there is a predetermined set of questions or unstructured whereby no questions are decided in advance.
The main strength of self-report methods are that they are allowing participants to describe their own experiences rather than inferring this from observing participants.
Questionnaires and interviews are often able to study large samples of people fairly easy and quickly. They are able to examine a large number of variables and can ask people to reveal behaviour and feelings which have been experienced in real situations.
However participants may not respond truthfully, either because they cannot remember or because they wish to present themselves in a socially acceptable manner. Social desirability bias can be a big problem with self report measures as participants often answer in a way to portray themselves in a good light.
Questions are not always clear and we do not know if the respondent has really understood the question we would not be collecting valid data.
If questionnaires are send out, say via email or through tutor groups, response rate can be very low.
Questions can often be leading. That is, they may be unwittingly forcing the respondent to give a particular reply.

Unstructured interviews can be very time consuming and difficult to carry out whereas structured interviews can restrict the respondents’ replies.
Therefore psychologists often carry out semi-structured interviews which consist of some pre-determined questions and followed up with further questions which allow the respondent to develop their answers.

Open and closed questions.

Questionnaires and interviews can use open or closed questions – or both.
Closed questions are questions which provide a limited choice – for example a participant’s age or their favourite type of cheese. Such questions provide quantitative data which is easy to analyse. However these questions do not allow the participant to give such in-depth insights.
Open questions are those questions which invite the respondent to provide their own answers and provide qualitative data. Although these type of questions are more difficult to analyse they can produce more in-depth responses relating to what the participant actually thinks rather than being restricted by categories.

Rating scales

One of the most common rating scales is the Likert scale. A statement is used and the participant decides how strongly they agree or disagree with the statements. For example the participant decides whether they strongly agree/ agree/ undecided/ disagree/ strongly disagree that Mozzarella cheese is great.
A strength of Likert type scales is that they can give us an idea about how strongly a participant feels about something. This therefore gives more detail than a simple yes no answer.
A further strength is that the data are quantitative data which are easy to analyse statistically.
However there is a tendency with Likert scales for people to respond towards the middle of the scale perhaps to make them look less extreme.
As with any questionnaire participants may provide the answers that they feel they should and importantly as the data is quantitative it does not provide in depth replies.

Fixed choice questions

Fixed choice questions are phrased so that the respondent has to make a fixed choice answer usually ‘yes’ or ‘no’.
This type of questionnaire is easy to measure and quantify. It also forces a participant to not choose a middle option.
However respondents may not feel that their desired response is available and of course the answers are not in-depth.

Reliability

Reliability refers to how consistent a measuring device is. A measurement is said to be reliable or consistent if the measurement can produce similar results if used again in similar circumstances. For example, if a speedometer gave the same readings at the same speed it would be reliable. If it didn't it would be pretty useless and unreliable.
Importantly reliability of self-report measures, such as psychometric tests and questionnaires can be assessed using the split half method. This involves splitting a test into two and having the same participant doing both halves of the test. If the two halves of the test provide similar results this would suggest that the test has internal reliability.
There are a number of ways to improve the reliability of self-report techniques. For example ambiguous questions could be clarified or in the case of interviews the interviewers could be given training.

Validity

Validity refers to whether a study measures or examines what it claims to measure or examine. Questionnaires are said to often lack validity for a number of reasons. Participants may lie; give answers that are desired and so on. It is argued that qualitative data is more valid than quantitative data.
A way of assessing the validity of self report measures is to compare the results of the self report with another self report on the same topic. (This is called concurrent validity). For example if an interview is used to investigate sixth grade students' attitudes toward smoking, the scores could be compared with a questionnaire of former sixth graders' attitudes toward smoking.
There are a number of ways to improve the validity of self report techniques. For example leading questions could be avoided, open questions could be added to allow respondents to expand upon their replies and confidentiality could be reinforced to allow respondents to give more truthful responses.

Disadvantages

Self-report studies have many advantages, but they also suffer from specific disadvantages due to the way that subjects generally behave. Self-reported answers may be exaggerated; respondents may be too embarrassed to reveal private details; various biases may affect the results, like social desirability bias

Social desirability bias

Social desirability bias is the tendency of respondents to answer questions in a manner that will be viewed favorably by others. It can take the form of over-reporting good behavior or under-reporting bad behavior. The tendency poses a serious problem with conducting research with self-reports,...

. Subjects may also forget pertinent details. Self-report studies are inherently biased by the person's feelings at the time they filled out the questionnaire. If a person feels bad at the time they fill out the questionnaire, for example, their answers will be more negative. If the person feels good at the time, then the answers will be more positive.

It is also possible for results to be biased by a lack of respondents, if there are systematic differences between people who respond and people who do not. Care must be taken to avoid biases due to interviewers and their demand characteristics

Demand characteristics

In research, and particularly psychology, demand characteristics refers to an experimental artifact where participants form an interpretation of the experiment's purpose and unconsciously change their behavior accordingly. Pioneering research was conducted on demand characteristics by Martin Orne...

.