Which of the following statements are true?

Note that there may be more than one correct answer; select all that are true.

If the two populations are not normally distributed , then the inference procedures for the difference between twomeans can still be valid , provided the sample sizes are large.The sampling distribution of* – *, is approximately normal , provided the independent sampling distributions of* , and * , are themselves approximately normal .The results obtained from the pooled – variance I procedure Versus the Welch procedure , when applied to the samedata set , will always be significantly different .One problem with taking observations on the same experimental unit , as in a paired difference test , is that it canincrease the variability in the experiment .The paired difference procedure is less susceptible to the populations being non – normal , since taking the difference*between two non – normal populations will result in a normal distribution .