Question

If the sample size is small (under 30), then: a) not to worry because the t-test is robust b) use the prop.test instead c) we must asses the data set for normality d) none of the above

Answer 1

Option a

Not to worry because the t test is robust

If the sample size is less than 30, we cannot use the Z test, but instead of Z test we can use t test and t test holds up strongly for smaller sample size and whenever the population standard deviation is unknown.

Student's t test allows the extreme values in a sample size a higher weightage(probability) than z test, since in a smaller sample size there is higher chance of extreme values occurring compared to in z test where same size is large.