These can be applied only when the components are more than 5. If the summed responses fulfils these assumptions, parametric statistical tests such as the analysis of variance can be applied. 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.
from the Learning Technology Dissemination Initiative] Chi-square test, Mann-Whitney test, Wilcoxon signed-rank test, or Kruskal-Wallis test. 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. Further, if the item is accompanied by a visual analog scale, where equal spacing of response levels is clearly indicated, the argument for treating it as interval-level data is even stronger. On the other hand, often (as in the example above) the wording of response levels clearly implies a "symmetry" of response levels about a middle category at the very least, such an item would fall between ordinal- and interval-level measurement to treat it as merely ordinal would lose information. Many regard such items only as ordinal data, because, especially when using only five levels, one cannot assume that respondents perceive all pairs of adjacent levels as equidistant. Whether individual Likert items can be considered as interval-level data, or whether they should be considered merely ordered-categorical data is the subject of disagreement. Hence, Likert scales are often called summative scales. Designing a scale with balanced keying (an equal number of positive and negative statements) can obviate the problem of acquiescence bias, since acquiescence on positively keyed items will balance acquiescence on negatively keyed items, but central tendency and social desirability are somewhat more problematic.Īfter 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. 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"). Likert scales may be subject to distortion from several causes. 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 scaling is a bipolar scaling method, measuring either positive or negative response to a statement. The format of a typical five-level Likert item is:: Often five ordered response levels are used, although many psychometricians advocate using seven or nine levels a recent empirical study found that data from 5-level, 7-level and 10-level items showed very similar characteristics in terms of mean, variance, skewness and kurtosis after a simple transformation was applied. This is the source of much confusion it is better, therefore, to reserve the word 'Likert scale' to apply to the summated scale, and 'Likert item' to refer to an individual item.Ī Likert item is simply a statement which the respondent is asked to evaluate according to any kind of subjective or objective criteria generally the level of agreement or disagreement is measured. Because Likert items are often accompanied by a visual analog scale (e.g., a horizontal line, on which a subject indicates his or her response by circling or checking tick-marks), the items are sometimes called scales themselves.
The Likert Scale is the sum of responses on several Likert items. Sample question presented using a five-point Likert itemĪn important distinction must be made between a "Likert Scale" and a "Likert item". Title = A Technique for the Measurement of Attitudes The scale is named after Rensis Likert, who published a report describing its use. When responding to a Likert questionnaire item, respondents specify their level of agreement to a statement. A Likert scale (pronunciation in the field of Psychology varies between 'lick-urt' and 'lie-kurt', although the man for whom the scale is named used the former ] ) is a psychometric scale commonly used in questionnaires, and is the most widely used scale in survey research.
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