If a court acquits every defendant, they will never commit a Type I error.
A) True
B) False
2.
The probability of rejecting a true null hypothesis increases as the sample size increases.
A) True
B) False
3.
For a given level of significance, the critical value of Student's t increases as n increases.
A) True
B) False
4.
In a two-tailed hypothesis test with α = .05, a test statistic of t = 1.813 with d.f. = 15 leads one to reject the null hypothesis of a statistical test.
A) True
B) False
5.
The power of a test is the probability that the test will reject a false null hypothesis.
A) True
B) False
6.
The height of the power curve shows the probability of accepting a true null hypothesis
A) True
B) False
7.
Which is not true of p-values?
A) When they are small, we want to reject Ho.
B) They must be specified before the sample is taken.
C) They show the chance of Type I error if we reject Ho.
D) They do not require α to be specified a priori.
Use the following scenario to answer questions 8 to 10.
Dullco Manufacturing claims that its alkaline batteries last forty hours on average in a certain type of portable CD player. Tests on a random sample of 18 batteries showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours.
8.
The test statistic is
A) -1.980
B) -1.728
C) -2.101
D) -1.960
9.
In determining the p-value for reporting the study's findings, which of the following is true?
A) The p-value is less than .05.
B) The p-value is equal to .05.
C) The p-value is greater than .05.
D) The p-value cannot be determined without specifying α.
10.
In a left-tailed test at α = .05 we would
A) comfortably reject the claim.
B) comfortably accept the claim.
C) feel uncomfortable with either decision (too close).
D) switch to alpha of 0.01 for a more powerful test.
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Use the following scenario to answer questions 11 to 13.
A TV special said there is a 10 per cent incidence of sexually transmitted disease (STD) among all U.S. teens. A reporter for the Rockville Bugle, looking for a story, surveyed 260 randomly chosen teenagers, and found that 39 had been to a clinic for STD treatment. Use a right-tail test at α = .05.
11.
The test statistic is
A) 2.687
B) 2.758
C) .0256
D) 2.258
12.
The critical value is
A) 1.645
B) 1.658
C) 1.697
D) 1.960
13.
The p-value is
A) .0501
B) .0314
C) 2.258
D) .0036
14.
Which of the following statements is correct?
A) For a given level of significance, the critical value of Student's t increases as n increases.
B) A test statistic of t = 2.131 with d.f. = 15 leads to a clear-cut decision in a two-tailed test where α = .05.
C) It is harder to reject the null hypothesis when conducting a two-tailed test rather than a one-tailed test.
D) If we desire α = 0.10 then a p-value of 0.13 would lead us to reject the null hypothesis.
15.
John rejected a null hypothesis in a right-tailed test for a mean at α = .025 because his critical t value was 2.000 and his calculated t value was 2.345. We can be sure that
A) John did not commit Type I error.
B) John did not commit Type II error.
C) John committed neither Type I nor Type II error.
D) none of the above can definitely be concluded.
