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 analyzed using non-parametric tests, such as the Mann-Whitney test, the Wilcoxon signed-rank test, and the Kruskal-Wallis test.

When responses to several Likert items **are summed**, they may be treated as interval data measuring a latent variable. If the summed responses are **normally distributed**, parametric statistical tests such as** t-test** can be applied.