t-test is a significance test used to test about population mean(s). It may be used to examine the mean of one population or to compare two population means. A key assumption behind a t-test is the Normal distribution on the underlying population(s). In the sequel, the measurement scale of the variable(s) of interest should preferably be quantitative.

Example 1:

Suppose a stress indicator, ranging from 0 to 100, is used to examine the stress level in Hong Kong nursing students. Then, to examine if the mean stress level is over 50, we may perform a one-sample t-test on a sample of subjects provided stress score follows a Normal distribution.

Example 2:

Following Example 1, if we like to compare the stress level between the two gender groups, we may perform a two-independent samples t-test provided the stress score for each gender group follows a Normal distribution.