The z value is agreed by statisticians to be more proper than the t value when the sample is large.

Question

Quizplus · Accepted Answer

When the sample size is large (typically n > 30), the distribution of sample means approaches a normal distribution regardless of the population distribution. In this case, the z-value can be used as the standard error of the mean, which is more appropriate than the t-value. The t-value is only necessary when the sample size is small or the population standard deviation is unknown.

The Z Value Is Agreed by Statisticians to Be More