Deck 11: Estimation and Confidence Intervals

Question 1

A researcher estimates the 95% CI for a sample with a mean of M = 3.26 and a standard error ( $\sigma$ _M)of 0.91.What is the upper confidence limit for this interval?

A) 1.48
B) 2.35
C) 4.17
D) 5.04

Answer 1

5.04

Question 2

If the null hypothesis is inside the confidence interval,then the decision was likely to ______ using hypothesis testing.

A) reject the null hypothesis
B) retain the null hypothesis

Answer 2

retain the null hypothesis

Question 3

Which of the following best describes the goal of estimation?

A) to determine the extent to which a result is significant
B) to estimate the significance of a result
C) to narrow in on the true population mean by defining limits within which it is likely to be contained
D) to determine the extent to which a result is significant and to estimate the significance of a result

Answer 3

to narrow in on the true population mean by defining limits within which it is likely to be contained

Question 4

A researcher estimates the 90% CI for a sample with a mean of M = 8.9 and a standard error ( $\sigma$ _M)of 2.1.What is the confidence interval at this level of confidence?

A) 90% CI 4.8, 13.0
B) 90% CI 5.5, 12.4
C) 90% CI 6.8, 11.0
D) There is not enough information to answer this question.

Question 5

If the value stated by a null hypothesis is ______ the confidence interval,then the decision would likely be to reject the null hypothesis.

A) inside
B) outside

Question 6

A statistical procedure in which a sample statistic is used to estimate the value of an unknown population parameter is called ______.

A) an educated guess
B) appropriation
C) estimation
D) significance testing

Question 7

Which type of error is used to compute the confidence interval for one sample selected from a population with an unknown variance?

A) standard error
B) estimated standard error
C) estimated standard error for the difference
D) estimated standard error for the difference scores

Question 8

A researcher estimates the 95% CI for a sample with a mean of M = 3.26 and a standard error ( $\sigma$ _M)of 0.91.What is the lower confidence limit for this interval?

A) 1.48
B) 2.35
C) 4.17
D) 5.04

Question 9

A researcher concludes that stress levels are higher following a major versus a minor traffic accident (95% confidence interval [CI] 1.86-3.02).If the null hypothesis stated that there would be no difference (null hypothesis: $\mu$ = 0),then what is the effect size for this confidence interval?

A) Between 1.86% and 3.02% of the variability in stress levels can be accounted for by type of traffic accident.
B) Ratings of stress shifted more than 1.86 points in the population.
C) Ratings of stress shifted between 1.86 and 3.02 points in the population.
D) There is not enough information to answer this question.

Question 10

A researcher reports that college students consume an average of 3.6 alcoholic drinks per week.What is the interval estimate in this example?

A) 3.6
B) The interval estimate is not given.

Question 11

If the value stated by a null hypothesis is ______ the confidence interval,then the decision would have likely been to retain the null hypothesis.

A) inside
B) outside

Question 12

Which of the following explains why point estimation can be a useful procedure to estimate a population mean?

A) It defines the range of scores within which the population mean is likely to be contained.
B) The sample mean is equal to the population mean on average.
C) The sample mean is an unbiased estimator of the population mean.
D) The sample mean is equal to the population mean on average and the sample mean is an unbiased estimator of the population mean.

Question 13

Which type of error is used to compute the confidence interval for one sample selected from a population with a known variance?

A) standard error
B) estimated standard error
C) estimated standard error for the difference
D) estimated standard error for the difference scores

Question 14

A researcher estimates the 95% CI for a sample with a mean of M = 9.0 and a standard error ( $\sigma$ _M)of 1.03.What is the confidence interval at this level of confidence?

A) 95% CI 7.3, 10.7
B) 95% CI 8.0, 10.0
C) 95% CI 7.0, 11.0
D) There is not enough information to answer this question.

Question 15

If the null hypothesis is outside the confidence interval,then the decision was likely to ______ using hypothesis testing.

A) reject the null hypothesis
B) retain the null hypothesis

Question 16

A point estimate is typically reported with an interval estimate.Why?

A) Using only a point estimate is associated with low certainty.
B) The interval estimate gives researchers a higher level of confidence.
C) The interval estimate adds certainty to the estimate of the population mean.
D) All of these.

Question 17

A researcher compares the height of male executives in the United States to the average height of males ( $\mu$ = 67 in.).He determines that the average height of male executives is 70 in.(95% confidence interval [CI] 68-72).Based on this result,what would the decision have been for a hypothesis test?

A) reject the null hypothesis
B) retain the null hypothesis
C) there is not enough information to answer this question

Question 18

The confidence interval for samples selected from one or two populations with an unknown variance is computed using critical values from the t table.This is true for which of the following types of samples?

A) one sample
B) two-independent sample
C) related samples
D) all of these

Question 19

A researcher reports with 90% confidence that 31% to 37% of Americans believe in ghosts.What is the point estimate for this interval?

A) 31%
B) 34%
C) 37%
D) 31% to 37%

Question 20

The confidence interval for one sample selected from a population with a known variance is computed using a critical value for which type of test?

A) z test
B) t test
C) none
D) both A and B

Question 21

In a sample of 18 participants,a researcher estimates the 80% CI for a sample with a mean of M₁ - M₂ = 8.8 and an estimated standard error for the difference (S_{M1 - M2})of 1.8.What is the lower confidence limit for this interval?

A) 6.4
B) 7.0
C) 10.6
D) 11.2

Question 22

A researcher increases his level of confidence from 90% to 95%.What will happen to the precision of his estimate?

A) The estimate will be more precise.
B) The estimate will be less precise.
C) The precision of his estimate will not change.
D) It depends on the size of the population.

Question 23

Which of the following words best describes certainty?

A) inferential
B) significance
C) precision
D) confidence

Question 24

In a sample of 14 participants,a researcher estimates the 90% CI for a sample with a mean of M₁ - M₂ = 10.7 and an estimated standard error for the difference (S_{M1 - M2})of 2.9.What is the confidence interval at this level of confidence?

A) 90% CI 4.4, 17.0
B) 90% CI 5.5, 15.9
C) 90% CI 7.8, 13.6
D) There is not enough information to answer this question.

Question 25

In a sample of 28 participants,a researcher estimates the 95% CI for a sample with a mean of M = 1.5 and an estimated standard error (S_M)of 0.3.What is the confidence interval at this level of confidence?

A) 95% CI 1.0, 2.0
B) 95% CI 1.2, 1.8
C) 95% CI 0.9, 2.1
D) there is not enough information to answer this question

Question 26

In a sample of 26 participants,a researcher estimates the 90% CI for a sample with a mean of M_D = 0.6 and an estimated standard error for the difference scores (S_MD)of 0.1.What is the upper confidence limit for this interval?

A) 0.77
B) -0.5
C) 1.7
D) 2.5

Question 27

Which type of error is used to compute the confidence interval for two related samples selected from at least one population with an unknown variance?

A) standard error
B) estimated standard error
C) estimated standard error for the difference
D) estimated standard error for the difference scores

Question 28

In a sample of 18 participants,a researcher estimates the 80% CI for a sample with a mean of M₁ - M₂ = 8.8 and an estimated standard error for the difference (S_{M1 - M2})of 1.8.What is the upper confidence limit for this interval?

A) 6.4
B) 7.0
C) 10.6
D) 11.2

Question 29

In a sample of 20 participants,a researcher estimates the 95% CI for a sample with a mean of M = 5.4 and an estimated standard error (S_M)of 1.6.What is the upper confidence limit for this interval?

A) 2.1
B) 3.8
C) 7.0
D) 8.8

Question 30

The smaller the level of confidence,the ______ precise the estimate.

A) more
B) less

Question 31

In a sample of 17 participants,a researcher estimates the 90% CI for a sample with a mean of M_D = 7 and an estimated standard error for the difference scores (S_MD)of 2.2.What is the confidence interval at this level of confidence?

A) 90% CI 2.4, 11.6
B) 90% CI 3.2, 10.8
C) 90% CI 4.8, 9.2
D) There is not enough information to answer this question.

Question 32

In a sample of 26 participants,a researcher estimates the 90% CI for a sample with a mean of M_D = 0.6 and an estimated standard error for the difference scores (S_MD)of 1.1.What is the upper confidence limit for this interval?

A) -1.3
B) -0.5
C) 1.7
D) 2.5

Question 33

Which of the following is a characteristic of confidence intervals?

A) The less certain an estimate, the more precise the estimate.
B) The more certain an estimate, the less precise the estimate.
C) The less certain an estimate, the more precise the estimate, and the more certain an estimate, the less precise the estimate.

Question 34

In a sample of 30 participants,a researcher estimates the 95% CI for a sample with a mean of M₁ - M₂ = 0.7 and an estimated standard error for the difference (S_{M1 - M2})of 0.2.What is the confidence interval at this level of confidence?

A) 95% CI 0.4, 1.0
B) 95% CI 0.5, 0.9
C) 95% CI 0.3, 1.1
D) There is not enough information to answer this question.

Question 35

The larger the level of confidence,the ______ precise the interval estimate.

A) more
B) less

Question 36

Which type of error is used to compute the confidence interval for two independent samples selected from at least one population with an unknown variance?

A) standard error
B) estimated standard error
C) estimated standard error for the difference
D) estimated standard error for the difference scores

Question 37

In a sample of 20 participants,a researcher estimates the 99% CI for a sample with a mean of M_D = 3.7 and an estimated standard error for the difference scores (S_MD)of 0.2.What is the confidence interval at this level of confidence?

A) 99% CI 3.5, 3.9
B) 99% CI 3.2, 4.2
C) 99% CI 3.1, 4.3
D) There is not enough information to answer this question.

Question 38

A researcher reduces her level of confidence from 99% to 90%.What will happen to the precision of her estimate?

A) The estimate will be more precise.
B) The estimate will be less precise.
C) The precision of her estimate will not change.
D) It depends on the size of the population.

Question 39

In a sample of 20 participants,a researcher estimates the 95% CI for a sample with a mean of M = 5.4 and an estimated standard error (S_M)of 1.6.What is the lower confidence limit for this interval?

A) 2.1
B) 3.8
C) 7.0
D) 8.8

Question 40

In a sample of 12 participants,a researcher estimates the 80% CI for a sample with a mean of M = 22.3 and an estimated standard error (S_M)of 4.7.What is the confidence interval at this level of confidence?

A) 80% CI 12.1, 32.5
B) 80% CI 17.6, 27.0
C) 80% CI 15.9, 28.7
D) there is not enough information to answer this question

Question 41

A researcher states that the average child acquires 2.6 taste aversions in his or her lifetime.This is an example of a point estimate.

Question 42

A matched-pairs design is one example of a situation in which it is appropriate to use the estimation formula for the related samples t.

Question 43

The smaller the level of confidence,the more precise the estimate.

Question 44

Confidence intervals can be interpreted in terms of the effect size.

Question 45

A point estimate is associated with a high level of confidence that the estimate is in fact equal to the population mean.

Question 46

There is no difference between a point estimate and an interval estimate.

Question 47

The population variance must be known to estimate the population mean for the one-sample z.

Question 48

The estimation formula for the one-sample z is M ± z( $\sigma$ _M).

Question 49

The least certain,but most precise,estimate is a point estimate.

Question 50

Two types of estimation are point estimation and interval estimation.

Question 51

The estimation formula for the related samples t is M_D ± t(s_{M1 - M2}).

Question 52

When the null hypothesis is outside a confidence interval,this indicates that it would likely be retained with hypothesis testing.

Question 53

Researchers can infer decisions made in hypothesis testing based on information provided by confidence intervals.

Question 54

The estimation formula for the one-sample t is M ± t(s_M).

Question 55

For the same data,increasing the certainty of an estimate will result in a less precise estimate.

Question 56

The estimated standard error is used in the formula to estimate the population mean for the one-sample z.

Question 57

The estimated standard error is used in the formula to estimate the population mean for the one-sample t.

Question 58

To estimate the population mean for the two-independent-sample t,the sample size must be known.

Question 59

The estimation formula for the two-independent-sample t is M₁ - M₂ ± t(s_MD).

Question 60

As the standard error increases,the precision of an estimate also increases.