Likert scales are named after Rensis Likert, who invented them in the early 1930s. They turn up in most questionnaires, usually in the form of response options such as:
1 Strongly agree
2 Weakly agree
3 Neither agree nor disagree
4 Weakly disagree
5 Strongly disagree
Another variant is the visual analogue Likert-style scale. This occurs in various forms. Here’s one form, from Wikipedia:
Here’s another form, where the participant draws a vertical line through the horizontal scale line at the point of their choice. The initial line has a label at each end, like this:
The participant now draws a vertical line (shown below in blue) at the appropriate point on the horizontal line:
The researcher measures the distance along the horizontal line to where the vertical line is placed; that gives a score. In the example below, that score would be 78.
Usually these scales are 100 mm long, so the researcher can measure an exact value from 0 to 100, so can use much more powerful statistics on the data (and use much smaller sample sizes) than would be the case with a five point scale like the one in the Wikipedia example above.
Analysis
Likert scales and Likert-style scales look straightforward – up to the point where you start to analyse the results. If you’re doing your analysis right, you’ll be able to give confident, well-informed answers to questions such as:
•What’s the difference between a Likert scale and a Likert item?
•Are you assuming that your data are on an interval scale or some other scale?
•How have you checked for external validity in your data?
•What allowance have you made for Miller’s findings on cognitive limitations in your choice of number of response options?
•Which statistical test will you use to check for statistical significance in your data?
Make sure you can answer these questions before you start using Likert-style scales for your questionnaire.
Copyleft Hyde & Rugg 2021