A Likert scale involves a series of statements that respondents may choose from in order to rate their responses to evaluative questions (Vogt, 1999). It is commonly used to measure attitudes, knowledge, or perceptions. Typically it will be a five (or seven) point scale with a neutral point in the middle (for example, strongly agree, agree, neither agree nor disagree, disagree, strongly disagree). You can also use a Likert scale with an even number of options, but be aware this is forcing the respondent to take a position (which you may or may not want to do).
When using a Likert scale you are accepting an assumption that the strength/intensity of an attitude is linear (i.e. on a continuum from strongly agree to strongly disagree) and that attitudes can be measured. This has the advantage that it collects degrees of opinion, and even no opinion at all, rather than forcing the respondent into a yes/no answer. When using the scale it is important that the scale is balanced either side of the mid-point (e.g. you should not have a scale made up of four positive and one negative options). It is also helpful for analysis if you ensure that your scales always have the same coding direction (e.g. agree is always coded as a lower (or higher) number than disagree).
Likert scales are not limited to measuring agreement and can be used to measure many other topics including:
We have produced a downloadable sheet with some of the more frequently used 5 and 7 point Likert scales available here: