# Quiz 7: Overview of Statistical Hypothesis Testing: the Z-Test

Psychology

Q 1Q 1

Inferential statistics are used to
A)decide whether sample data represent a particular relationship in the population.
B)get rid of sampling error.
C)improve sampling error.
D)decide whether the population causes a particular relationship in the sample data.

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A

Q 2Q 2

Which of the following assumptions are common to all parametric statistics?
A)There are no common assumptions.
B)The population of dependent scores forms a normal distribution, regardless of what kind of scores they are.
C)The dependent scores must be interval or ratio scores, regardless of whether the population of scores forms a normal distribution.
D)The population of dependent scores a) must be interval or ratio scores and b) must form an approximately normal distribution.

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D

Q 3Q 3

Which of the following is correct regarding experimental hypotheses?
A)We can prove a predicted relationship exists in a population by confirming an experimental hypothesis.
B)They describe the population parameters to be tested by the experiment.
C)They describe the predicted relationship we may or may not find in an experiment.
D)We can prove theories about behavior by confirming experimental hypotheses.

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C

Q 4Q 4

When is a one-tailed test used?
A)When no relationship is predicted
B)When a relationship is predicted and the direction in which the scores will change is predicted
C)When the demonstrated relationship is predicted
D)When a relationship is predicted without stating the direction in which the scores will change

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Q 5Q 5

Which of the following is correct regarding statistical hypotheses null hypothesis and alternative hypothesis)?
A)They describe the population parameters our sample data represent if there is or is not a predicted relationship.
B)They describe the sample data if there is or is not a relationship in the population.
C)We can prove a relationship exists in the population by confirming these hypotheses.
D)They are the hypotheses we perform on the statistics in our experiment.

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Q 6Q 6

Which of the following is true of any one-sample experiment?
A)We must know the population mean under the same condition of the independent variable as the one being tested.
B)We must know the population mean under some condition of the independent variable other than the one being tested.
C)We must know the sample mean under the condition of the independent variable being tested, but we do not need to know the population mean.
D)We must know the sample mean under the condition of the independent variable being tested and under some other condition of the independent variable.

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Q 7Q 7

Which of the following is correct regarding alternative hypotheses?
A)They are alternatives to the experimental hypotheses.
B)They state the predicted relationship if the sample statistic does not fall in the region of rejection.
C)They describe the population parameters represented by the sample data if the predicted relationship exists.
D)They describe the population parameters represented by the sample data if the predicted relationship does not exist.

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Q 8Q 8

If a sample mean is different from a particular population , we can conclude the sample mean probably represents some other population or else
A)the sample mean does not represent the sample statistic.
B)an error was made in calculating the sample mean.
C)an error was made in calculating standard error.
D)the sample mean occurred as a result of sampling error.

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Q 9Q 9

Which of the following statements does not belong
A)Our condition of the independent variable produced a significant difference in the dependent scores.
B)The change in the dependent scores was produced by significant sampling error.
C)We obtained a significant z.
D)There is a significant effect of the condition.

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Q 10Q 10

When experimental results are significant, this means the hypothesis has been .
A)experimental; rejected
B)alternative; rejected
C)null; accepted
D)null; rejected

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Q 11Q 11

When statisticians report results as nonsignificant, the results are
A)not due to chance.
B)not important.
C)not too unlikely to accept as representing the same population.
D)different from what was expected or predicted.

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Q 12Q 12

Which of the following accurately defines a Type I error?
A)Rejecting when is true
B)Rejecting when is false
C)Retaining when is true
D)Retaining when is false

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Q 13Q 13

Which of the following accurately defines a Type II error?
A)Rejecting when it is true
B)Rejecting when it is false
C)Failing to reject when it is true
D)Failing to reject when it is false

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Q 14Q 14

What happens to the probability of committing a Type I error if the level of significance is changed from α = .01 to α = .05?
A)The probability of committing a Type I error will decrease.
B)The probability of committing a Type I error will increase.
C)The probability of committing a Type I error will remain the same.
D)The change in probability will depend on your sample size.

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Q 15Q 15

Which of the following tests is considered to be more powerful?
A)A one-tailed test
B)A two-tailed test
C)Neither; they are both equally statistically powerful
D)Which is more powerful depends on the sample size

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Q 16Q 16

The power of a statistical test is the probability of
A)failing to reject a false .
B)failing to reject a true .
C)rejecting a false .
D)rejecting a true .

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Q 17Q 17

A nonparametric procedure would not be done in conjunction with
A)ratio distributions.
B)a skewed interval distribution.
C)computing the median.
D)computing the mode.

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Q 19Q 19

Which is not an assumption of a z-test?
A)The dependent variable is perfectly normal and must involve an interval scale.
B)We know the mean of the population of raw scores under another condition of the independent variable.
C)We have randomly selected one variable.
D)We know the true standard deviation of the population.

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Q 20Q 20

How would you report a nonsignificant z-obtained value of -.50 in a journal article?
A)z = -.50, p > .05
B)z = -.50, p < .05
C)z = .50, p > .05
D)z = -.50, p > .50

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Q 21Q 21

Suppose a researcher has made a decision that a certain pill is not effective at treating depression when, in reality, it is.What has the researcher done in this case?
A)The researcher has made a Type II error.
B)The researcher has made a Type I error.
C)The researcher has made a correct decision to reject the null hypothesis.
D)The researcher has made a correct decision to reject the alternative hypothesis.

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Q 24Q 24

If the difference between your sample mean and the known population mean is 1.961, and your population standard deviation is 5, how big of a sample size would you need to get a significant result using α = .05 and a two-tailed test?

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Q 26Q 26

The Physical Fitness Test National Level for Girls) shows the national average for 10yearold girls on "rightangle pushups" to be μ = 13.Principal Smyth hypothesizes her girls at Strong School are significantly above the national mean.If the = 6 and the scores for nine girls are as reported here, compute and determine if Principal Smyth is right.Use α = .05.
14 16 18 16 12 16 17 20 15

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Q 28Q 28

The population mean for the Elementary Tenacity Test ETT) is 150 with A recent study of elementary school children participating in a school lunch program obtained the following ETT scores.Use a two-tailed z-test and

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Q 29Q 29

If you have and conduct a two-tailed z-test.Use α = .05.Be sure to set up your hypotheses and rejection region, calculate your z-score, and state your decision.

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Q 30Q 30

If you have and conduct a two-tailed z-test.Use α = .05.Be sure to set up your hypotheses and rejection region, calculate your z-score, and state your decision.

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Q 31Q 31

If you have and conduct a two-tailed z-test.Use α = .01.Be sure to set up your hypotheses and rejection region, calculate your z-score, and state your decision.

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Q 32Q 32

Given and conduct a two-tailed z-test.Use α = .05.Be sure to set up your hypotheses and rejection region, calculate your z-score, and state your decision.

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Q 33Q 33

Given and conduct a two-tailed z-test.Use α = .01.Be sure to set up your hypotheses and rejection region, calculate your z-score, and state your decision.

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Q 34Q 34

Suppose you conduct an experiment, and the is statistically nonsignificant at −0.65.How would you correctly report this result?

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Q 35Q 35

Suppose you conduct an experiment, and your is statistically significant at +3.45.How would you correctly report this result?

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Q 36Q 36

If = +2.21, do you reject or fail to reject using a one-tailed test in the upper tail with α = .05?

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Q 37Q 37

If = -2.11 do you reject or fail to reject using a one-tailed test in the upper tail with α = .05?

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Q 38Q 38

If you have and conduct a one-tailed z-test for a lower mean.Use α = .05.Be sure to set up your hypotheses and rejection region, calculate your z-score, and state your decision.

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Q 39Q 39

Given and conduct a two-tailed z-test.Use α = .05.Be sure to set up your hypotheses and rejection region, calculate your z-score, and state your decision.

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Q 40Q 40

Given and conduct a one-tailed z-test in the upper tail.Use α = .05.Be sure to set up your hypotheses and rejection region, calculate your z-score, and state your decision.

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Q 41Q 41

To determine whether a new drug designed to lower a person's heart rate is effective or not, Dr.Johnson gives the medicine to a random sample of 100 patients with Rapid Heart Rhythm RHR) and obtains a sample mean of 128.Dr.Johnson knows the heart rate of the population of individuals with RHR is 135 with .If Dr.Johnson uses a one-tailed test and α = .05, what is the appropriate conclusion?

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Q 42Q 42

If the probability that you will reject a that is false is 0.85, what is the probability you will commit a Type II error?

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Q 44Q 44

Suppose a researcher develops a drug designed to promote sleep.Those who take this drug, on average, sleep for
8.1 hours per night whereas those who do not take it sleep for 7.5 hours per night.In the context of this study, what would the alternative hypothesis suggest?

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Q 45Q 45

Suppose a researcher develops a drug designed to promote sleep.Those who take this drug, on average, sleep for
8.1 hours per night whereas those who do not take it sleep for 7.5 hours per night.In the context of this study, what would the null hypothesis suggest?

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