Deck 8: Hypothesis Testing: Significance, Effect Size, and Power

Question 1

If a researcher obtains a null finding,then what is the decision?

A)They correctly rejected the null hypothesis.
B)They incorrectly rejected the null hypothesis.
C)They correctly retained the null hypothesis.
D)They failed to make a decision.

Answer 1

C

Question 2

What is the typical level of significance for a hypothesis test in behavioral research?

A).05
B).10
C).001
D).50

Answer 2

A

Question 3

A professor gives an exam in which the mean score is 78 points.She gives another exam to test whether or not scores change.In this example,the null hypothesis is

A) $\neq$ 78
B)M $\neq$ 78
C) = 78
D)M = 78

Answer 3

= 78

Question 4

A researcher directly controls for the probability of a ________,but does not directly control for the probability of a ________.

A)Type I error;alpha level
B)Type II error;beta level
C)Type I error;Type II error
D)Type II error;Type I error

Question 5

Which of the following is not one of the four steps to hypothesis testing?

A)state the hypotheses
B)evaluate the plan
C)set the criteria for a decision
D)compute the test statistic

Question 6

In Step 2 of hypothesis testing,researchers state a level of significance to minimize the probability of

A)rejecting a true null hypothesis
B)retaining a false null hypothesis
C)inflating the power of a decision
D)all of the above

Question 7

Which of the following statements regarding the null hypothesis is true?

A)The null hypothesis always makes statements about a population parameter.
B)A decision in hypothesis testing is made about the alternative hypothesis,not the null hypothesis.
C)The null hypothesis is the only hypothesis stated in hypothesis testing.
D)all of the above

Question 8

A researcher believes that increasing attention given to children will improve mean academic performance.Therefore,the alternative hypothesis should be:

A)mean academic performance will increase
B)mean academic performance will decrease
C)mean academic performance will not change
D)mean attention will increase

Question 9

The first step to hypothesis testing requires that a researcher

A)state the hypotheses
B)make a decision
C)compute a test statistic
D)conduct a study

Question 10

In hypothesis testing,a researcher can never

A)compute a test statistic before making a decision
B)make decisions about the null hypothesis
C)prove that his or her hypothesis is correct
D)know the likelihood of obtaining a sample mean if the null hypothesis were true

Question 11

A researcher computes a test statistic and finds that the p value for this test is .03.What does this result mean?

A)There is a 3% likelihood of obtaining the test statistic value,if the null were true.
B)The probability of committing a Type I error if we retain the null hypothesis is 3%.
C)The probability of committing a Type II error if we reject the null hypothesis is 3%.
D)There is a 3% likelihood that the researcher's hypothesis is correct.

Question 12

A method for testing a claim or hypothesis about a parameter in a population,using data measured in a sample,is called

A)random sampling
B)level of significance
C)hypothesis testing
D)guessing

Question 13

In hypothesis testing,a researcher's decision

A)is based on a probability
B)depends on the level of significance for a hypothesis test
C)can be to retain or reject the null hypothesis
D)all of the above

Question 14

If the value of the test statistic is in the rejection region,then

A)p < .05
B)the decision is to reject the null hypothesis
C)the value of the test statistic is larger than the critical value
D)all of the above

Question 15

Hypothesis testing is also called

A)Type III error
B)random testing
C)effect size
D)significance testing

Question 16

Suppose a researcher wants to make sure that the probability of committing a Type I error is less than 5%.How can the researcher control for this?

A)Set the value for a Type II error at .05.
B)Set the alpha level at .05.
C)Place the rejection region in both tails.
D)both B and C

Question 17

Researchers state a level of significance in terms of an alpha level.The alpha level indicates

A)the probability of committing a Type I error
B)the probability of incorrectly rejecting the null hypothesis
C)the probability value for the rejection region
D)all of the above

Question 18

What are the two decisions that researchers can make in hypothesis testing?

A)accept or reject the null hypothesis
B)retain or reject the null hypothesis
C)both A and B are correct

Question 19

Which of the following best describes the p value.

A)It is the same as an alpha level
B)It is a conditional probability
C)Its value must be greater than .05 to reject the null hypothesis
D)all of the above

Question 20

The criteria for a decision regarding the value stated in a null hypothesis is set by the

A)level of significance
B)p value
C)probability value
D)both A and B

Question 21

Based on the effect size conventions,d = 0.99 is a

A)small effect size
B)medium effect size
C)large effect size

Question 22

A researcher obtains z = -6.45.What is the decision for a one-tailed test,upper-tail critical,at a .05 level of significance?

A)to reject the null hypothesis
B)to retain the null hypothesis
C)It depends on the sample size.
D)There is not enough information to make a decision.

Question 23

A researcher obtains z = 1.45 for a one-sample z test.What is the decision for this test at a .05 level of significance?

A)to reject the null hypothesis
B)to retain the null hypothesis
C)It depends on whether the test is one-tailed or two-tailed.
D)There is not enough information to make a decision.

Question 24

Based on the effect size conventions,d = 0.18 is a

A)small effect size
B)medium effect size
C)large effect size

Question 25

A researcher selects a sample of 36 students from a school population with a mean IQ of 100 and standard deviation of 12.She determines that the mean IQ in this sample is 104.Assuming she computes a one-sample z test at a .05 level of significance,what is the decision for a two-tailed test?

A)Retain the null hypothesis;IQ scores in this sample are the same as those in the population.
B)Reject the null hypothesis;IQ scores in this sample are significantly higher than those in the population.
C)There is not enough information to make a decision.

Question 26

When a researcher decides to retain the null hypothesis because the rejection region was located in the wrong tail,this is called a

A)Type I error
B)Type II error
C)Type III error
D)correct decision

Question 27

A researcher reports that the size of an effect in Population A is d = 0.10 and the effect size in Population B is d = 0.34.Which population is associated with greater power to detect an effect?

A)Population A
B)Population B
C)They are associated with the same level of power.

Question 28

Given the following values:
= 10,M = 8,
= 0.5,conduct a one-sample z test at a .05 level of significance.What is the decision for a two-tailed test?

A)to reject the null hypothesis
B)to retain the null hypothesis
C)There is not enough information since the sample size is not given.

Question 29

A researcher obtains z = 1.80 for a one-sample z test.What is the decision for this test at a .05 level of significance?

A)to reject the null hypothesis
B)to retain the null hypothesis
C)It depends on whether the test is one-tailed or two-tailed.

Question 30

Given the following values:
= 6.0,M = 7.6,n = 36,
= 6,conduct a one-sample z test at a .05 level of significance.For a one-tailed test,upper-tail critical,what is the decision?

A)to reject the null hypothesis
B)to retain the null hypothesis
C)There is not enough information since the sample size is not given.

Question 31

________ allows researchers to describe (1)how far mean scores have shifted in the population,or (2)the percentage of variance that can be explained by a given variable.

A)significance
B)probability
C)power
D)effect size

Question 32

A measure of the size of an effect in a population is called

A)significance
B)probability
C)power
D)effect size

Question 33

A researcher obtains z = 2.04 for a one-sample z test.What is the decision for this test at a .05 level of significance?

A)to reject the null hypothesis
B)to retain the null hypothesis
C)It depends on whether the test is one-tailed or two-tailed.
D)There is not enough information to make a decision.

Question 34

A professor finds that the average SAT score among all students attending his college is 1150±150 (
).He polls his class of 25 students and finds that the average SAT score is 1200.Suppose he computes a one-sample z test at a .05 level of significance.What is his decision?

A)to reject the null hypothesis
B)to retain the null hypothesis
C)to reject the null hypothesis for a two-tailed test,but to retain the null hypothesis for an upper-tailed test
D)to reject the null hypothesis for an upper-tailed test,but to retain the null hypothesis for a two-tailed test

Question 35

A researcher obtains z = 3.98 for a one-sample z test.If her decision is to retain the null hypothesis,then what do you know about her decision?

A)Her decision was inconclusive.
B)Her decision was based on a two-tailed test.
C)Her decision resulted in a Type III error.
D)both A and B

Question 36

The one-sample z test is a hypothesis test used to test hypotheses

A)concerning a single population with a known variance
B)concerning at least one population
C)concerning the variance in a population
D)all of the above

Question 37

A researcher reports that the size of an effect in some population is d = 0.88.Which of the following is an appropriate interpretation for d?

A)The effect observed in the population was significant.
B)Mean scores were significant by 0.88 points in the sample.
C)Mean scores were significant by 0.88 points in the population.
D)Mean scores shifted 0.88 standard deviations in the population.

Question 38

Based on the effect size conventions,d = 0.60 is a

A)small effect size
B)medium effect size
C)large effect size

Question 39

The probability of committing a Type I error is stated by ________;the probability for committing a Type II error is stated by ________.

A)beta;alpha
B)alpha;beta
C)a p value;a p value
D)the power;the power

Question 40

The power of the decision-making process is

A)stated by an alpha level
B)the likelihood of rejecting a false null hypothesis
C)the same as a null finding
D)the likelihood of committing a Type I error

Question 41

Rejecting a true null hypothesis is a Type I error.

Question 42

Following the steps to hypothesis testing allows researchers to make decisions about parameters in a sample using statistics measured in a population.

Question 43

The alpha level is basically the same thing as the p value.

Question 44

One step to hypothesis testing is to set the criteria for a decision.

Question 45

A researcher reports the following result for a one-sample z test at a .05 level of significance: z  1.88,p  .06 (d  .25).Is this result significant?

A)Yes,the decision is to reject the null hypothesis
B)Yes,because the effect size is large hypothesis
C)No,the decision is to retain the null hypothesis
D)No,because the effect size is small hypothesis

Question 46

When reporting the results of a one-sample z test using APA format,the ________ does not need to be reported.

A)Test statistic
B)p value
C)effect size
D)critical values

Question 47

Increasing sample size will

A)Increase the alpha level.
B)Increase the likelihood of committing a Type I error.
C)Increase the power of the decision.
D)All of the above.

Question 48

A researcher reports that scores were higher than the mean in the population,z  1.60,p  .05 (d  .14).If this was a test at a .05 level of significance,then what value must be incorrectly reported?

A)The effect size
B)The p value
C)The alpha level
D)The test statistic

Question 49

A researcher reports that the standard deviation in Population A is
= 2.3 and the standard deviation in Population B is
= 4.3.Which population is associated with the highest power to detect an effect?

A)Population A
B)Population B
C)They are associated with the same level of power.

Question 50

Which of the following is a scenario in which increasing sample size will increase power

A)When the effect size is small.
B)When the effect size is large.
C)When the probability of a Type I error is small.
D)All of the above.

Question 51

The null hypothesis and alternative hypotheses are statements about parameters in the population.

Question 52

Researchers directly control for the probability of committing a Type II error.

Question 53

A researcher conducts a study,but has low power to detect an effect.Which of the following is one way in which the research can increase power?

A)Make the alpha level smaller.
B)Increase the sample size.
C)Study a population with a larger standard deviation.
D)Conduct the study again with the same sample size.

Question 54

A researcher conducts two studies.Each study was a one-sample z test.Both studies placed the rejection region in both tails and measured the same sample mean.The alpha level in Study 1 was larger than the alpha level used in Study 2.Which study is associated with greater power to detect an effect?

A)Study 1
B)Study 2
C)They are associated with the same level of power.

Question 55

Is a one-sample z test reported differently for one-tailed and two-tailed tests?

A)No,the same values are reported.
B)It depends on whether the results were significant.
C)Yes,only significant results for a two-tailed test are reported.
D)It can be reported differently when the effect size is large.

Question 56

A null finding is a decision to retain a null hypothesis that is correct.

Question 57

A researcher computes a one-sample z test in two studies.Both studies used the same alpha level,placed the rejection region in both tails,and measured the same sample mean.The researcher selects a sample of 30 participants in Study 1 and decides to retain the null hypothesis.She selects a sample of 60 participants in Study 2 and decides to reject the null hypothesis.Which of the following is the best explanation for why the decision was different in Study 1 and Study 2?

A)The different decisions in Study 1 and Study 2 are not possible because all values were the same.
B)The different decisions in Study 1 and Study 2 are not possible because the researcher tested the same hypothesis.
C)The different decisions in Study 1 and Study 2 are due to an error the researcher made in the first hypothesis test.
D)The different decisions in Study 1 and Study 2 are possible because the second test was associated with greater power to detect an effect.

Question 58

The typical level of significance in hypothesis testing in the behavioral sciences is set at .05.

Question 59

The probability of correctly rejecting a false null hypothesis is called the power of the decision-making process.

Question 60

A researcher tests a hypothesis to prove whether or not his or her hypothesis is correct.

Question 61

The test statistic determines whether or not an effect exists in a population;effect size measures the size of an observed effect in a population.

Question 62

The critical values are reported with the test statistic of a one-sample z test using APA format.

Question 63

For the one-sample z test,the larger the value of a test statistic,the less likely it is that differences observed in the study are due to error.

Question 64

Assuming that the rejection region is placed in the correct tail,the power of detecting an effect is larger for one-tailed tests compared with two-tailed tests.

Question 65

The z statistic is a z transformation for a distribution of sample means.

Question 66

The alpha level must be split into each tail for a directional hypothesis test.

Question 67

An effect size of d = 0.68 is a large effect in the population.

Question 68

The z statistic measures the size of an effect in some population.

Question 69

A researcher computes a z statistic and obtains z = 2.10.If this were a one-tailed (lower-tail critical)test,then the decision would be to reject the null hypothesis.

Question 70

As effect size increases,the power to detect an effect decreases.

Question 71

A null finding is one in which the null hypothesis is incorrectly rejected.

Question 72

As the population standard deviation increases,the power to detect an effect increases.

Question 73

As sample size increases,the power to detect an effect increases.

Question 74

The value of power is influenced by the alpha level,sample size,and effect size.

Question 75

The p value is reported with the test statistic of a one-sample z test using APA format.

Question 76

Cohen's d is a measure of how far mean scores have shifted in a population.

Question 77

One-tailed tests will rarely,if ever,result in decisions that are different from two-tailed tests in hypothesis testing.

Question 78

The greater the power,the less likely we are to correctly reject the null hypothesis,if it is incorrect.

Question 79

A Type III error is only possible for hypothesis tests where the rejection region is located in one tail.

Question 80

A large effect size means that Cohen's d is at least equal to .80.