Likert Scales vs Semantic Differential Scales
Rating scales are the backbone of many questionnaires. Two of the most widely used are the Likert scale and the semantic differential scale. They look similar on the page but measure attitudes in different ways. In this blog, we'll explain how each works, where each fits best, and what to consider when choosing.
The Likert Scale:
- Respondents rate how much they agree or disagree with a statement, for example from "Strongly disagree" to "Strongly agree".
- It is named after Rensis Likert, who developed the approach in the 1930s.
- Several related items are usually combined into a total or average score to measure one construct, such as job satisfaction.
- It is familiar to most respondents and easy to administer.
The Semantic Differential Scale:
- Respondents rate a concept on a scale between two opposite adjectives, such as "Unhelpful" and "Helpful" or "Cheap" and "Expensive".
- It was developed by Charles Osgood and colleagues to measure the meaning people attach to concepts.
- It is often used to measure perceptions of brands, products, services or people.
Key Differences:
- A Likert item asks for agreement with a statement; a semantic differential item asks where a concept sits between two opposites.
- Semantic differential items can be quicker to answer and less wordy, but they need carefully chosen adjective pairs.
- Likert items can express more complex ideas, but they can be affected by a general tendency to agree.
How to Choose:
- Use a Likert scale when you want to measure beliefs, attitudes or experiences that are best expressed as statements.
- Use a semantic differential scale when you want to capture how people perceive or evaluate a specific object, such as a brand or service.
- Check what validated scales in your field already use. Following an established scale is often the best choice.
Practical Tips:
- Keep the number of points consistent within a section, commonly five or seven.
- Label the scale points clearly, at least at both ends.
- For semantic differential scales, vary which side the positive adjective appears on, and pilot the pairs to make sure they are true opposites to your respondents.
- Decide in advance how you will analyse the data, and follow the conventions in your field for reporting it.
Both scales are useful tools. Likert scales suit statements about attitudes and experiences, while semantic differential scales suit evaluations of a specific object. Choose the one that fits what you want to measure, keep your formatting consistent, and pilot your items before full data collection.