Deck 9: One-Sample Hypothesis Tests

Question 1

Compared to using α = .01,choosing α = .001 will make it less likely that a true null hypothesis will be rejected.

Answer 1

True

Question 2

John rejected H0,so we know definitely that he did not commit a Type II error.

Answer 2

True

Question 3

A hypothesis test may be statistically significant,yet have little practical importance.

Answer 3

True

Question 4

If a judge acquits every defendant,the judge will never commit a Type I error.(H0 is the hypothesis of innocence. )

Question 5

When your sample size increases,the chance of both Type I and Type II error will increase.

Question 6

For a given sample size and α level,the Student's t value always exceeds the z value.

Question 7

For a given level of significance (α),increasing the sample size will increase the probability of Type II error because there are more ways to make an incorrect decision.

Question 8

A two-tailed hypothesis test for H0: μ = 15 at α = .10 is analogous to asking if a 90 percent confidence interval for μ contains 15.

Question 9

A simultaneous reduction in both α and β will require a larger sample size.

Question 10

In hypothesis testing,we cannot prove a null hypothesis is true.

Question 11

The probability of a false positive is decreased if we reduce α.

Question 12

For a given level of significance,the critical value of Student's t increases as n increases.

Question 13

A Type II error can only occur when you fail to reject H0.

Question 14

The level of significance refers to the probability of making a Type II error.

Question 15

For a given sample size,reducing the level of significance will decrease the probability of making a Type II error.

Question 16

A false positive in a drug test for steroids is a Type II error.

Question 17

When the probability of a Type I error increases,the probability of a Type II error must decrease,ceteris paribus.

Question 18

The probability of rejecting a false null hypothesis increases as the sample size increases,other things being equal.

Question 19

The level of significance refers to the probability of making a Type I error.

Question 20

A Type I error can only occur if you reject H0.

Question 21

Holding other factors constant,it is harder to reject the null hypothesis for a mean when conducting a two-tailed test rather than a one-tailed test.

Question 22

Other things being equal,a large population standard deviation would weaken the power of a test for one mean.

Question 23

If the hypothesized proportion is π0 = .025 in a sample of size 120,it is safe to assume normality of the sample proportion p.

Question 24

For a sample of nine items,the critical value of Student's t for a left-tailed test of a mean at α = .05 is −1.860.

Question 25

If we desire α = .10,then a p-value of .13 would lead us to reject the null hypothesis.

Question 26

A null hypothesis is rejected when the calculated p-value is less than the critical value of the test statistic.

Question 27

In a right-tailed test,the null hypothesis is rejected when the value of the test statistic exceeds the critical value.

Question 28

The probability of rejecting a true null hypothesis is the significance level of the test.

Question 29

If the null and alternative hypotheses are H0: μ ≤ 100 and H1: μ > 100,the test is right-tailed.

Question 30

For a given H0 and level of significance,if you reject the H0 for a one-tailed test,you would also reject H0 for a two-tailed test.

Question 31

In the hypothesis H0: π = π0,the value of π0 is derived from the sample.

Question 32

Power is the probability of rejecting the null hypothesis when it is false and is equal to 1 − β.

Question 33

In testing the hypotheses H0: π ≤ π0,H1: π > π0,we would use a right-tailed test.

Question 34

For a given null hypothesis and level of significance,the critical value for a two-tailed test is greater than the critical value for a one-tailed test.

Question 35

The null hypothesis is rejected when the p-value exceeds the level of significance.

Question 36

The p-value is the probability of obtaining the sample result (or one more extreme),assuming H0 is true.

Question 37

The critical value of a hypothesis test is based on the researcher's selected level of significance.

Question 38

For a mean,we would expect the test statistic to be near zero if the null hypothesis is true.

Question 39

To test the hypothesis H0: π = .0125 using n = 160,it is safe to assume normality of p.

Question 40

In testing a proportion,normality of p can be assumed if nπ0 ≥ 10 and n(1 − π0)≥ 10.

Question 41

After testing a hypothesis,we decided to reject the null hypothesis.Thus,we are exposed to

A)Type I error.
B)Type II error.
C)either Type I or Type II error.
D)neither Type I nor Type II error.

Question 42

The power of a test is the probability that the test will reject a false null hypothesis.

Question 43

You are driving a van packed with camping gear (total weight 3,500 pounds including yourself and family)into a northern wilderness area.You take a "short cut" that turns into a one-lane road,with no room to turn around.After 11 miles you come to a narrow bridge with a faded sign saying,"Safe Up to 2 Tons." About a half-mile ahead,you can see that your road rejoins the main highway.You consider the sign's hypothesis carefully before making a decision.The cost of Type I error is

A)that you pass safely over the bridge and everyone's happy.
B)about $23,900,not including medical bills.
C)that you will find out just how cold that river actually is.
D)that your kids will think you are a chicken.

Question 44

After testing a hypothesis regarding the mean,we decided not to reject H0.Thus,we are exposed to

A)Type I error.
B)Type II error.
C)either Type I or Type II error.
D)neither Type I nor Type II error.

Question 45

In hypothesis testing,we are trying to prove the null hypothesis.

Question 46

Which of the following is incorrect?

A)The level of significance is the probability of making a Type I error.
B)Lowering both α and β at once will require a larger sample size.
C)The probability of rejecting a true null hypothesis increases as n increases.
D)When Type I error increases,Type II error must decrease,ceteris paribus.

Question 47

In hypothesis testing,we are trying to reject the alternative hypothesis.

Question 48

Larger samples lead to increased power,ceteris paribus.

Question 49

For a given sample size,when we increase the probability of a Type I error,the probability of a Type II error

A)remains unchanged.
B)increases.
C)decreases.
D)is impossible to determine without more information.

Question 50

Which of the following statements is correct?

A)Increasing α will make it more likely that we will reject H0,ceteris paribus.
B)Doubling the sample size roughly doubles the test statistic,ceteris paribus.
C)A higher standard deviation would increase the power of a test for a mean.
D)The p-value shows the probability that the null hypothesis is false.

Question 51

"I believe your airplane's engine is sound," states the mechanic."I've been over it carefully,and can't see anything wrong.I'd be happy to tear the engine down completely for an internal inspection at a cost of $1,500.But I believe that roughness you heard in the engine on your last flight was probably just a bit of water in the fuel,which passed harmlessly through the engine and is now gone." As the pilot considers the mechanic's hypothesis,the cost of Type I error is

A)the pilot will experience the thrill of no-engine flight.
B)the pilot will be out $1,500 unnecessarily.
C)the mechanic will lose a good customer.
D)impossible to determine without knowing α.

Question 52

A study over a 10-year period showed that a certain mammogram test had a 50 percent rate of false positives.This indicates that

A)about half the tests indicated cancer.
B)about half the tests missed a cancer that exists.
C)about half the tests showed a cancer that did not exist.
D)about half the women tested actually had no cancer.

Question 53

When σ is unknown,it is more conservative to use z instead of t for the critical value.

Question 54

As you are crossing a field at the farm,your country cousin Jake assures you,"Don't worry about that old bull coming toward us.He's harmless." As you consider Jake's hypothesis,what would be Type I error on your part?

A)You will soon feel the bull's horns.
B)You will run away for no good reason.
C)Jake will not have any more visits from you.

Question 55

Which of the following is correct?

A)When the sample size increases,β may decrease and power would increase.
B)Type II error can only occur when you reject H0.
C)Type I error can only occur if you fail to reject H0.
D)The level of significance is the probability of Type II error.

Question 56

John rejected his 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 a Type I error.
B)John did not commit a Type II error.
C)John committed neither a Type I nor Type II error.
D)John committed both a Type I and a Type II error.

Question 57

"My careful physical examination shows no evidence of any serious problem," said Doctor Morpheus."However,a very costly lab test can be performed to check for the rare condition known as estomalgia fatalis.The test is almost invariably negative for persons with your age and symptoms.My personal hypothesis is that the occasional stomach pain you reported is due to indigestion caused by eating tacos with too much hot sauce.But you must decide for yourself." As you consider your doctor's hypothesis,what would be the consequence of Type I error on your part?

A)It cannot be determined without knowing the type of test.
B)Your estomalgia fatalis will go undetected.
C)You will waste money on an unnecessary lab test.
D)Your survivors will enjoy a sizeable malpractice award.

Question 58

After lowering the landing gear,the pilot notices that the "gear down and locked" light is not illuminated."It's probably just a burned out light bulb," she says,as she proceeds on final approach for landing.Considering the pilot's hypothesis,which is the result of Type I error?

A)The sound of metal scraping on concrete will be heard upon landing.
B)The landing is delayed unnecessarily while the bulb and gear are checked.
C)We cannot be sure without knowing whether or not the bulb is actually faulty.

Question 59

A smaller probability of Type II error implies higher power of the test.

Question 60

Which statement about α is not correct?

A)It is the probability of committing a Type I error.
B)It is the test's significance level.
C)It is the probability of rejecting a true H0.
D)It is equal to 1 − β.

Question 61

For tests of a mean,if other factors are held constant,which statement is correct?

A)The critical value of Student's t increases as n increases.
B)A test statistic tcalc = 1.853 with n = 16 leads to rejection at α = .05 in a one-tailed test.
C)It is harder to reject the null hypothesis in a two-tailed test rather than a one-tailed test.
D)If we desire α = .10,then a p-value of .13 would lead us to reject the null hypothesis.

Question 62

Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player.But tests on a random sample of 18 batteries from a day's large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours.To test DullCo's hypothesis,the p-value is

A)slightly less than .05.
B)exactly equal to .05.
C)slightly greater than .05.
D)uncertain without knowing α.

Question 63

Which of the following is not a valid null hypothesis?

A)H0: μ ≥ 0
B)H0: μ ≤ 0
C)H0: μ ≠ 0
D)H0: μ = 0

Question 64

The level of significance is not

A)the probability of a "false rejection."
B)a value between 0 and 1.
C)the likelihood of rejecting the null hypothesis when it is true.
D)the chance of accepting a true null hypothesis.

Question 65

For a right-tailed test of a hypothesis for a population mean with n = 14,the value of the test statistic was t = 1.863.The p-value is

A)between .05 and .025.
B)between .10 and .05.
C)greater than .10.
D)less than .01.

Question 66

For a sample size of n = 100,and σ = 10,we want to test the hypothesis H0: μ = 100.The sample mean is 103.The test statistic is

A)1.645
B)1.960
C)3.000
D)0.300

Question 67

Which of the following is not a characteristic of the t distribution?

A)It is a continuous distribution.
B)It has a mean of zero.
C)It a symmetric distribution.
D)It is similar to the z distribution when n is small.

Question 68

In testing a proportion,which of the following statements is incorrect?

A)Using α = 0.05 rather than α = .01 would make it more likely that H0 will be rejected.
B)When the sample proportion is p = .02 and n = 150,it is safe to assume normality.
C)An 80 percent confidence interval is narrower than the 90 percent confidence interval,ceteris paribus.
D)The sample proportion may be assumed approximately normal if the sample is large enough.

Question 69

Hypothesis tests for a mean using the critical value method require

A)using a two-tailed test.
B)sampling a normal population.
C)knowing the true population mean.
D)specifying α in advance.

Question 70

Which is not a likely reason to choose the z distribution for a hypothesis test of a mean?

A)The value of σ is known.
B)The sample size n is very large.
C)The population is normal.
D)The value of σ is unknown.

Question 71

Which is not true of p-values?

A)When they are small,we want to reject H0.
B)They measure the probability of an incorrect decision.
C)They show the chance of Type I error if we reject H0.
D)They do not require α to be specified a priori.

Question 72

Given a normal distribution with σ = 3,we want to test the hypothesis H0: μ = 20.We find that the sample mean is 21.The test statistic is

A)1.000
B)1.645
C)1.960
D)impossible to find without more information.

Question 73

Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player.But tests on a random sample of 18 batteries from a day's large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours.In a left-tailed test at α = .05,which is the most accurate statement?

A)We would strongly reject the claim.
B)We would clearly fail to reject the claim.
C)We would face a rather close decision.
D)We would switch to α = .01 for a more powerful test.

Question 74

For a test of a mean,which of the following is incorrect?

A)H0 is rejected when the calculated p-value is less than the critical value of the test statistic.
B)In a right-tailed test,we reject H0 when the test statistic exceeds the critical value.
C)The critical value is based on the researcher's chosen level of significance.
D)If H0: μ ≤ 100 and H1: μ > 100,then the test is right-tailed.

Question 75

The critical value in a hypothesis test

A)is calculated from the sample data.
B)usually is .05 or .01 in most statistical tests.
C)separates the acceptance and rejection regions.
D)depends on the value of the test statistic.

Question 76

Guidelines for the Jolly Blue Giant Health Insurance Company say that the average hospitalization for a triple hernia operation should not exceed 30 hours.A diligent auditor studied records of 16 randomly chosen triple hernia operations at Hackmore Hospital and found a mean hospital stay of 40 hours with a standard deviation of 20 hours."Aha!" she cried,"the average stay exceeds the guideline." At α = .025,the critical value for a right-tailed test of her hypothesis is

A)1.753
B)2.131
C)1.645
D)1.960

Question 77

Guidelines for the Jolly Blue Giant Health Insurance Company say that the average hospitalization for a triple hernia operation should not exceed 30 hours.A diligent auditor studied records of 16 randomly chosen triple hernia operations at Hackmore Hospital and found a mean hospital stay of 40 hours with a standard deviation of 20 hours."Aha!" she cried,"the average stay exceeds the guideline." The value of the test statistic for her hypothesis is

A)2.080
B)0.481
C)1.866
D)2.000

Question 78

When testing the hypothesis H0: μ = 100 with n = 100 and σ2 = 100,we find that the sample mean is 97.The test statistic is

A)−3.000
B)−10.00
C)−0.300
D)−0.030

Question 79

Guidelines for the Jolly Blue Giant Health Insurance Company say that the average hospitalization for a triple hernia operation should not exceed 30 hours.A diligent auditor studied records of 16 randomly chosen triple hernia operations at Hackmore Hospital and found a mean hospital stay of 40 hours with a standard deviation of 20 hours."Aha!" she cried,"the average stay exceeds the guideline." The p-value for a right-tailed test of her hypothesis is

A)between .05 and .10.
B)between .025 and .05.
C)between .01 and .025.
D)less than .01.

Question 80

Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player.But tests on a random sample of 18 batteries from a day's large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours.To test DullCo's hypothesis,the test statistic is

A)−1.980
B)−1.728
C)−2.101
D)−1.960