1.Student'sttest for correlated groups really reduces to _________.

a.

the sign test

b.

Student'sttest for single samples using difference scores

c.

Studentsttest for independent groups

d.

none of the above

2. The z test for independent groups is seldom used because _________.

1. it lacks sensitivity
2. it is too complicated
3. we seldom know the population variances
4. the sampling distribution of z under H0 is unknown

3.In a t test, when the size of the sample is increased, the confidence interval _________.

1. increases
2. decreases
3. stays the same
4. changes shape
5. a and d

4. As the df increases, the t distribution _________.

1. gets more symmetrical
2. approaches the normal distribution
3. stays the same
4. becomes more skewed