T-Test with Likert Scale Variables

Abstract

Although Likert scale is numeric, it is intrinsically ordinal (1 – Strongly disagree to 5 - Strongly agree). Even ordinal, due to convenience it is usual to use a t-test to evaluate whether two groups are significantly different (testing population mean with unknown variance). In this paper I will investigate if when we have a survey that uses a Likert Scale, it is adequate to use a t-test. I will use bootstrapping by first “imposing” that the population verifies the null hypothesis. I conclude that, the use of the t-test it is valid to compare groups even when the variable is measured a Likert scale and the populations does not have a normal distribution.