Ch. 9

On average, what value is expected for the t statistic when the null hypothesis is true? 1 0 t > 1.96 1.96

0

A sample of n = 25 scores has a mean of M = 40 and a standard deviation of s = 10. What is the estimated standard error for the sample mean? 2 1 4 5

2

A researcher conducts a hypothesis test using a sample from an unknown population. If the t statistic has df = 30, how many individuals were in the sample? n = 29 n = 38 n = 31 n = 30

n = 31

With α = .01, the two-tailed critical region for a t test using a sample of n= 16 subjects would have boundaries of ______. t = ±2.583 t = ±2.921 t = ±2.947 t = ±2.602

t = ±2.947

Which set of characteristics will produce the smallest value for the estimated standard error? A small sample size and a large sample variance A large sample size and a small sample variance A small sample size and a small sample variance A large sample size and a large sample variance

A large sample size and a small sample variance

Under what circumstances can a very small treatment effect be statistically significant? If the sample size and the sample variance are both small If the sample size and the sample variance are both big If the sample size big and the sample variance is small If the sample size is small and the sample variance is big

If the sample size big and the sample variance is small

When n is small (less than 30), how does the shape of the t distribution compare to the normal distribution? It is taller and narrower than the normal distribution. It is almost perfectly normal. It is flatter and more spread out than the normal distribution. There is no consistent relationship between the t distribution and the normal distribution.

It is flatter and more spread out than the normal distribution.

If other factors are held constant, what is the effect of increasing the sample size? It will increase the estimated standard error and increase the likelihood of rejecting H0. It will decrease the estimated standard error and increase the likelihood of rejecting H0. It will decrease the estimated standard error and decrease the likelihood of rejecting H0. It will increase the estimated standard error and decrease the likelihood of rejecting H0.

It will decrease the estimated standard error and increase the likelihood of rejecting H0.

If other factors are held constant, which set of sample characteristics is most likely to reject a null hypothesis stating that M = 80? M = 85 and small sample variance M = 90 and large sample variance M = 90 and small sample variance M = 85 and large sample variance

M = 90 and small sample variance

Which of the following is a fundamental difference between the t statistic and a z-score? The t statistic uses the sample variance in place of the population variance. The t statistic computes the standard error by dividing the standard deviation by n- 1 instead of dividing by n. All of these are differences between t and z. The t statistic uses the sample mean in place of the population mean.

The t statistic uses the sample variance in place of the population variance.