1. A hypothesis using a single-sample t-test test produces a t statistic of t = 2.20. If the researcher is using a two-tailed test with = .05, which of the following is the correct statistical decision? Hint: Find the critical region for alpha .05 and alpha .01 for this test.

The researcher can reject the null hypothesis with either = .05 or = .01.

The researcher can reject the null hypothesis with = .05 but not with = .01.

The researcher must fail to reject the null hypothesis with either = .05 or = .01.

It is impossible to make a decision about H₀ without the sample size for the degrees of freedom.

2. If other factors are held constant, what is the effect of increasing the sample size on the size of the estimated standard error and the likelihood of rejecting the null hypothesis (H₀)?

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

It will decrease 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.

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

3. Tryptophan is the chemical in turkey meat and other Thanksgiving favorites thought to induce sleepiness. You give a sample of n = 30 subjects a shot of tryptophan and ask them to rate their sleepiness on a scale of 0 (not sleepy at all) to 10 (very sleepy). You find that the mean sleepiness rating for your sample is M = 8 with a standard deviation of s = 3. From a previous study, you have found that the mean sleepiness rating for those who got a full night's rest is = 4. You do not have access to the population standard deviation. Is there enough evidence to support that tryptophan has any effect on sleepiness? Set alpha at = .05.

What does the NULL HYPOTHESIS say about the effect of tryptophan on sleepiness?

Tryptophan is correlated to sleepiness.

Trypotphan has an effect on sleepiness.

None of the other answers are correct.

Trypotphan has no effect on sleepiness.