What a questionnaire is

1. A questionnaire collects data through a set of written questions that the participant fills in themselves.
2. It is a self-report method like the interview, but nobody is present while the answers are given.
3. Because it is written, the same questions can go to a whole year group at once, or to hundreds of people online.

Closed questions and quantitative data

1. A closed question gives the participant a fixed set of options to choose between.
2. The answers come back as counts or numbers, which makes them quantitative data.
3. Quantitative data is quick to total, easy to put in a table or a bar chart and simple to compare between people.
4. The cost is that a fixed set of options can push someone into an answer that is not quite true for them.

Open questions and qualitative data

1. An open question leaves space for the participant to answer in their own words.
2. The answers come back as written descriptions, which makes them qualitative data.
3. Qualitative data explains why someone thinks what they think, which no tick box can ever show.
4. The cost is that answers vary wildly in length and content, so sorting and comparing them takes a great deal of time.

When to choose a questionnaire

1. Choose it when you need a large sample and there is no time or money for interviewing everyone.
2. Choose it when the topic is private, because writing an answer alone is easier than saying it to someone's face.
3. Choose an interview instead when you expect to have to explain a question or chase an unexpected answer.

Strengths

1. They gather a lot of data quickly and cheaply, and closed answers arrive in a fixed form that takes very little work to total and compare.
2. Privacy encourages honesty, because nobody is watching the participant write, so social desirability bias is usually weaker than in a face to face interview.

Weaknesses

1. A misread question cannot be rescued, because nobody is there to explain it, so a participant may answer something you never asked.
2. Many people never reply, and those who do are often unusually keen or unusually annoyed, which biases your sample.

Turning this into marks

1. Write out the answer options whenever you are asked for a closed question.
2. For an open question, check the wording cannot be answered with yes or no.
3. The mark most often lost is on improving a question, where you must name the fault and then give the corrected wording.