The Likert scale is one type of rating scale often used in UX surveys. It allows you to obtain from the questioner his opinion on a given topic - perception, preferences or beliefs. What exactly is it and where can it be checked?
What is the Likert Scale?
Asking questions and answering them, taking into account the scale of assessments, appear in many methodologies of activities and research methods. Most often they take the form of surveys, but also usability tests. Proper interpretation of the results helps to understand how customers see the service or product. This, in turn, provides access to information about the user experience, which is extremely important for creating a quality solution.
The Likert scale owes its name to Rensis Likert, an American educator, psychologist and sociologist who worked for 30 years as head of the Institute for Social Research at the University of Michigan. He created the author's method of assessment in the 1930s. What exactly is it? A measure of compliance with a set of statementsthat the respondents receive. The task of the respondents is to determine to what extent they agree with the observations. Interpretation of the results occurs after analyzing the answers to all questions.
The Likert scale is Interval Bipolar Scale — this means that on opposite sides of this scale there are beliefs of opposite significance. The word interval means ranking the points of the scale assuming equal distance between them. Where is the Likert scale used? An example is the usability assessment questionnaires, e.g. SUS System Usability Scale and in SUPR-Q Satisfaction Measurement Questionnaire (eng. Standardized User Experience Percentile Rank Questionnaire).
Variants of the Likert Scale that can be used in usability tests
There are three variants of the Likert scale. The most popular of these is the currently used variant 5-pointHowever, you can also use the version 4-item scale without a neutral point (otherwise called the forced choice scale), and 7-item scale, in which there is 1 additional answer on both sides of the neutral point.
5-point Likert scale is characterized by the occurrence of a central tendency error. This is one of the most common cognitive errors, which consists in a great reluctance to choose the answers, placed at the end of the scale. Most raters choose to give an average rating, rather than a harsh one. This error does not only apply to filling out surveys - but also to everyday life. In schools, the most common grades are threes and fours. A grade of 1 or 6 is given much less often. For this reason, when using a 5-point scale, there is a high possibility of obtaining neutral answers.
To solve the problem of indicating the middle elements of the scale, another has been introduced scale — 4-step, called the forced choice scale, devoid of a neutral point. As it were, this version forces the person filling out the questionnaire to make a decision regarding the assessment of the statement in question. It does not give him the opportunity to remain neutral. This design of the survey requires a longer reflection on the answer - so it can be more adequate. However, if the respondent does not have an opinion on a given topic - it can lead to falsification of the results.
Measurement accuracy was to increase the introduction 7-point Likert scale. Each page was followed by one additional response — “I agree” and “I disagree”. This scale increases the measurement accuracy for individual statements, but as the number of questions increases, this effect decreases. In addition, if until now the surveys were conducted using a 5-point scale, the transition to a 7-point scale takes away the possibility of comparative analysis. The results interpreted at the time usability studies, carried out on other sites, are unproductive.
How to count the Likert scale?
The first step in the research methodology that will allow the correct application of the Likert scale is to determine the questions that are appropriate for a given group of people. Example of a question:
“I feel confident using the system.”
Responses (assuming a 5-point Likert scale):
- I strongly disagree,
- I do not agree,
- I don't know/I don't have an opinion,
- I agree,
- I definitely agree.
It may be a good idea to introduce the presentation of data in graphic form, in the form of smiley, neutral and sad emoticons. The Likert scale collects responses as numerical value, no matter in what form they are given. Calculations are reduced to deriving the average of the answers obtained and stating which answers of the respondents were chosen most often.
Each of the variants of the Likert scale has advantages and disadvantages. No matter which one the interviewer chooses — the key to success is to develop the right questions. Then the selection of scale will be secondary. Looking for help with UX and UI design — contact us! We will do our best to find the best solutions for you.
