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A Likert scale (variously pronounced 'lick-urt' or 'lie-kurt') is a type of psychometric response scale often used in questionnaires, and is the most widely used scale in survey research. When responding to a Likert questionnaire item, respondents specify their level of agreement to a statement. The scale is named after Rensis Likert, who published a report describing its use (Likert, 1932).

Contents 1 Sample question presented using a five-point Likert Scale 2 Scoring and analysis 3 Level of measurement 4 Rasch model 5 Pronunciation 6 References 7 See also 8 External links

A typical test item in a Likert scale is a statement. The respondent is asked to indicate his or her degree of agreement with the statement or any kind of subjective or objective evaluation of the statement. Traditionally a five-point scale is used, however many psychometricians advocate using a seven or nine point scale.

1. Strongly disagree
2. Disagree
3. Neither agree nor disagree
4. Agree
5. Strongly agree

Likert scaling is a bipolar scaling method, measuring either positive or negative response to a statement. Sometimes a four-point scale is used; this is a forced choice method since the middle option of "Neither agree nor disagree" is not available. Likert scales may be subject to distortion from several causes. Respondents may avoid using extreme response categories (central tendency bias); agree with statements as presented (acquiescence bias); or try to portray themselves or their organization in a more favorable light (social desirability bias).

After the questionnaire is completed, each item may be analyzed separately or in some cases item responses may be summed to create a score for a group of items. Hence, Likert scales are often called summative scales.

Responses to a single Likert item are normally treated as ordinal data, because, especially when using only five levels, one cannot assume that respondents perceive the difference between adjacent levels as equidistant. When treated as ordinal data, Likert responses can be collated into bar charts, central tendency summarised by the median or the mode (but not the mean), dispersion summarised by the range across quartiles (but not the standard deviation), or analyzed using non-parametric tests, e.g. Chi-square test, Mann-Whitney test, Wilcoxon signed-rank test, or Kruskal-Wallis test.^[1]

Responses to several Likert questions may be summed, providing that all questions use the same Likert scale and that the scale is a defendable approximation to an interval scale, in which case they may be treated as interval data measuring a latent variable. If the summed responses fulfils these assumptions, parametric statistical tests such as the analysis of variance can be applied. These can be applied only when the components are more than 5.

Data from Likert scales are sometimes reduced to the nominal level by combining all agree and disagree responses into two categories of "accept" and "reject". The Chi-Square, Cochran Q, or McNemar-Test are common statistical procedures used after this transformation.

Consensus based assessment (CBA) can be used to create an objective standard for Likert scales in domains where no generally accepted standard or objective standard exists. Consensus based assessment (CBA) can be used to refine or even validate generally accepted standards.

The five response categories are often believed to represent an Interval level of measurement. But this can only be the case if the intervals between the scale points correspond to empirical observations in a metric sense. In fact, there may also appear phenomena which even question the ordinal scale level. For example, in a set of items A,B,C rated with a Likert scale circular relations like A>B, B>C and C>A can appear. This violates the axiom of transitivity for the ordinal scale.

Likert scale data can, in principle, be used as a basis for obtaining interval level estimates on a continuum by applying the polytomous Rasch model, when data can be obtained that fit this model. In addition, the polytomous Rasch model permits testing of the hypothesis that the statements reflect increasing levels of an attitude or trait, as intended. For example, application of the model often indicates that the neutral category does not represent a level of attitude or trait between the disagree and agree categories.

Again, not every set of Likert scaled items can be used for Rasch measurement. The data has to thoroughly be checked to fulfill the strict formal axioms of the model.

If one were to rely on standard American English phonology to determine the pronunciation of the word 'Likert,' it would be pronounced 'like-urt,' with a long "i" sound. However, Rensis Likert, the developer of the scale pronounced his name 'lick-urt' with a short "i" sound (Babbie, 2005; Meyers, Guarino, & Gamst, 2005). It has been claimed that Likert's name "is among the most mispronounced in [the] field" (Latham, 2006, p. 15). Because of this distinction, although many people use the long "i" variant, those who attempt to stay true to Dr. Likert's pronunciation use the short "i" pronunciation.

Babbie, Earl R. (2005). The Basics of Social Research. Thomson Wadsworth, p. 174. ISBN 0534630367. 

Latham, Gary P. (2006). Work Motivation: History, Theory, Research, And Practice. Sage Publications Inc, p. 15. ISBN 0761920188. 

Likert, Rensis (1932), "A Technique for the Measurement of Attitudes", Archives of Psychology 140: pp. 1-55

Meyers, Lawrence S.; Anthony Guarino, Glenn Gamst (2005). Applied Multivariate Research: Design and Interpretation. Sage Publications Inc, p. 20. ISBN 1412904129. 

• Analog scale
• Guttman scale
• Ipsative
• Phrase completion scales
• Thurstone scale
• Mokken scale
• Bogardus Social Distance Scale
• F-scale
• Discan scale
• Diamond of opposites
• Rating scale
• Rating sites
• Reverse coding
• Voting system
• Consensus based assessment (CBA)

Trochim, William M. The Research Methods Knowledge Base, 2nd Edition. Internet WWW page, at URL: http://www.socialresearchmethods.net/kb/scallik.php (version current as of October 20, 2006).