When is the t distribution used instead of the Z distribution to test the significance of the difference between two sample means?
A)never
B)when sample size is very large
C)when one sample is much larger than the other
D)when N is small

Question

Quizplus · Accepted Answer

The t distribution should be used when the sample size is small (N < 30) and the population standard deviation is unknown. The smaller sample size also means that the sample standard deviation is likely to be a less accurate estimate of the population standard deviation, which makes the use of the t distribution more appropriate.

When Is the T Distribution Used Instead of the Z