It is a realization of a standard normal random variable, defined as a random variable with expected value 0 and variance 1. Therefore we generate random numbers from the distribution N(0,1).
t_{i,j} follows normal distribution with mean 0 and standard deviation 1. This information can be used to simulate t values using computing or statistical software. An online tutorial using Excel can be found here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7xkswPZF5i8.html
