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Basic Concepts in Questionnaire Design

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Dr Jurek Kirakowski,
Dept. Applied Psychology,
University College Cork, Ireland email:

There have been many definitions of what a questionnaire is; usually these definitions reflect the bias and working environments of the people who propose them. At its most general, I would say a questionnaire is a method for the elicitation, and recording, and collecting of information. At my university where I teach psychometrics, I usually give a 50-minute introductory lecture explaining this definition with examples and anecdotes, the notes below summarize the gist of it, concentrating on the four important italicized words.

Often one hears talk of reliability and validity. I give a summary of the accepted meaning of these terms at the end.

Questionnaires are made up of items to which the user supplies answers or reactions.

Answering a questionnaire focuses the respondent's mind to a particular topic and almost by definition, to a certain way of approaching the topic. We try hard to avoid bias when we construct questionnaires; when a respondent has to react to very tightly focussed questions (so-called closed-ended questionnaires) bias is a real problem. When a respondent has to react to a more loose set of questions (so-called open-ended), bias is still there, but it's most probably more deeply hidden.

What is meant by reliability?
The reliability of a questionnaire is the ability of the questionnaire to give the same results when filled out by like-minded people in similar circumstances. Reliability is usually expressed on a numerical scale from zero (very unreliable) to one (extremely reliable.)

What is meant by validity?
The validity of a questionnaire is the degree to which the questionnaire is actually measuring or collecting data about what you think it should be measuring or collecting data about. Note that not only do opinion surveys have validity issues; factual questionnaires may have very serious validity issues if for instance, respondents interpret the questions in different ways.

Dr Kirakowski is a Senior Lecturer in Applied Psychology and the Director of the Human Factors Research Group ( He is the author of the Software Usability Measurement Inventory ( and the Website Analysis and Measurement Inventory (

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