Definition: A semantic differential scale is a survey-based research technique used to capture ratings. The scale contains grammatically opposite adjectives at each end. For example, if asking about product reliability, you would have “unreliable” on the left and “reliable” on the right, with a fixed number of answer points in between.
Semantic Differential vs. Likert Scale: A Likert scale asks respondents to rate an item on a fixed scale, usually 1-5. The semantic differential scale forces respondents to pick between two words on how best to describe an item. Thus, the semantic differential scale allows respondents to gauge both ends of the scale better, making your data more reliable.
How would you rate our restaurant for the following?
Using an online survey with a semantic differential scale element is a great way to capture ratings about a common subject. Each row would be a sub-topic or attitude related to the topic. It's an improvement to standard rating questions or a Likert scale because it gives respondents an easy way to evaluate (or relate to) both sides of the scale. Here are some of the most common uses of a semantic differential scale, with an example of what can be measured:
The key to creating a Semantic Differential Scale is having contrasting adjectives (opposites) for each row/line/sub-question. On the SurveyKing platform, this can be accomplished in a few ways. Here is the recommended approach for creating a Semantic Differential Scale:
You could add these question types as a make-shift semantic differential scale. However, keep in mind that these are technically not semantic differential scales.
It is good practice to put negatively correlated adjectives on the left and positively correlated adjectives on the right. This helps to counteract social desirability and primacy bias. However, the left-to-right method also follows the same logic of established questions like Net Promoter Score. In addition, most modern speaking languages in Eurpotree, Noth America, and South America read from left to right, meaning the left-to-right scale is more intuitive.
The best practice is to keep the adjectives as short as possible, usually one word on each side. Ensure the words are the exact opposite or as clear as they can be. For example, if you wanted to ask about "reliability", you would not want to have "unreliable" and "long-lasting". Instead, use "unreliable" and "reliable."
You also want to limit the number of rows/items. Keep survey fatigue in mind. Only include rows that are fundamental to your study. Include no more than ten rows per question if possible.
The first semantic differential scale put into practice was a seven-point scale. Some studies recommend a five-point scale as optimal. Because many respondents will take your surveys on a mobile device where screen space is limited, we recommend using a five-point scale.
There is an additional option within the survey builder to randomize the rows within a semantic differential scale question. This randomization helps to eliminate bias by showing each row in a random order for each respondent.
When creating a research survey, a common question is whether to use a Likert or semantic differential scale. As previously mentioned, a Likert scale has fixed points, usually a simple 1-5 numeric scale. The semantic differential scale has a point scale but adjectives on each side.
If you're unsure what one to use, go with a semantic differential scale. This choice will be beneficial because it is easier for respondents to gauge both ends of the scale. For example, consider a restaurant feedback survey asking, "how friendly was the wait staff?" on a scale of 1-5. It might be ambiguous what a "1" actually is. If the waitstaff was not friendly, then even a "1" might infer that the respondent agreed that "friendly" was somewhat present.
This is one problem with the Likert scale; the wording might force a respondent to pick or agree with a trait that doesn't exist. Having "unfriendly" on the left and "friendly" on the right removes any ambiguity of the question. The respondent then has the flexibility to fill in the answer based on their feelings without any bias.
A semantic differential scale also forces you to keep the adjectives on the left and right short. As a result, fewer words reduce the time it takes to complete a survey and increase response rates.
There are no hard and fast rules on when to use a specific type. Generally, a Likert scale is used when you want to ask related questions requiring agreement. A semantic differential scale is best used when you have attitudes or characteristics you want to measure. Here are a few examples of when you could use each question type.
The results will give you a count of all rows and data points along with a weighted score for a semantic differential scale element type. The weighted score is simply the sum of all responses divided by the number of votes for that row. In addition, the results section will include a diverging bar chart with that weighted score, making it easy to evaluate how each row is being evaluated.
In the summary table, you'll notice that the range of values goes from -2 to 2. This is because the scale contains grammatically opposite adjectives at each end and having a scale that reflects that makes analysis, namely visualizing the data in a chart, easier.
When you download the Excel export, each row would have its own column. Below each column, the rows would contain the respondent score. This format makes it easy to calculate your own weighted average, make adjustment to the scale used, or carry out your own statistical analysis.
If you include additional question types to your survey, such as age range or gender, you could use these questions to create a cross-tabulation report. For example, this report would show the differences between "males" and "females." When you make this cross-tabulation report, you will get a data table for each segment you create.
Below is an example of both the semantic differential bar chart and data table.
While the semantic differential scale is an excellent research tool, it has limitations. The main limitation is that it does not measure relative importance. Consider an example where you are conducting market research for a product. You might have rows asking about price, reliability, and packaging. Price, for example, might score as "cheap," but how do you know if the price is a driving factor in the buying decision?
A question type like MaxDiff can help you measure the relative importance of the attributes that make up your product. With this data, you can then build optimal products. Generally, MaxDiff is the first step in market research. A Semantic Differential Scale can then be used for additional surveys to fine-tune the product.
Another limitation of Semantic Differential is the adjectives used on each end can be hard to determine. You need to be able to use short and straightforward adjectives that elicit a quick response. In addition, not all question types have contrasting adjectives. A Likert scale or simple rating can be used for these question types.
Charles E. Osgood is credited with creating the Semantic Differential Scale. In 1957 he co-authored a book titled "The Measurement of Meaning" which mentions there has not been much research done in the field of measuring traits or attributes in any standard way. The experiment in the book uses a 7-point semantic differential scale and then compares fifty descriptive scales' results. Finally, the book found that this approach was a valid measurement technique.