Likert scales are valuable because they allow researchers to quantify and analyze data that can be difficult to measure, such as attitudes and emotions. There is a very wide variety of coding scales that can be used for this, depending on what exactly is being measured.
In their most traditional form, Likert scales are a 5-point scale, where 1 is the lowest point on the scale, and 5 is the highest point on the scale. Traditionally, a Likert scale is bipolar, meaning that it captures both extremes of an attitude (strongly agree to strongly disagree), and it is an odd-point scale, meaning that it allows for neutral responses. Although the five-item scale is among the most common, Likert scales can have more or fewer items, depending on the needs. For example, a three-item scale would eliminate the need for respondents to report the degree to which they agree or disagree, while a four-item Likert scale would eliminate the Neutral option, forcing an opinion to be either positive or negative. By removing the neutral point from the scale, respondents are forced to provide a positive or negative response, which can help clients understand the directionality of their results without ambiguity. However, this also comes with the obvious trade-off of forcing “true” neutral respondents to provide a response that doesn’t reflect their real-life attitudes.
Here is an example of a traditional Likert scale. It has 5 points, has an equal number of options for positive and negative points in the scale (i.e. is a bipolar scale), and has contains a neutral option.
This is an example of a 5-point unipolar scale. While it has 5 points, it’s only measuring the magnitude of one variable, Interest. Thus, there is no negative point on the scale, and it is a unipolar scale. There is no true neutral option, but “Somewhat interested” serves as the middle point between the highest level of interest and the lowest level of interest.