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Determine the 95% confidence interval for Determine the 95% confidence interval for in each of the following cases: a) b) c) d) A comparison of the widths of the intervals obtained in (a), (b), and (c) suggests what generalization concerning the sampling variation of the correlation coefficient? in each of the following cases: a) Determine the 95% confidence interval for in each of the following cases: a) b) c) d) A comparison of the widths of the intervals obtained in (a), (b), and (c) suggests what generalization concerning the sampling variation of the correlation coefficient? b) Determine the 95% confidence interval for in each of the following cases: a) b) c) d) A comparison of the widths of the intervals obtained in (a), (b), and (c) suggests what generalization concerning the sampling variation of the correlation coefficient? c) Determine the 95% confidence interval for in each of the following cases: a) b) c) d) A comparison of the widths of the intervals obtained in (a), (b), and (c) suggests what generalization concerning the sampling variation of the correlation coefficient? d) A comparison of the widths of the intervals obtained in (a), (b), and (c) suggests what generalization concerning the sampling variation of the correlation coefficient?

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(a) -.49 to +.74
(b) -.19 to +...

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The practice of making confidence intervals of The practice of making confidence intervals of is recommended because A) it is more accurate than hypothesis testing B) it does not require the assumption of a normal bivariate distribution C) it calls attention more directly to the influence of sampling variation on r D) it takes better account of the number of degrees of freedom involved is recommended because


A) it is more accurate than hypothesis testing
B) it does not require the assumption of a normal bivariate distribution
C) it calls attention more directly to the influence of sampling variation on r
D) it takes better account of the number of degrees of freedom involved

E) A) and B)
F) A) and C)

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Which set of circumstances is most likely to result in a narrow confidence interval?


A) large n and a confidence level of .95
B) large n and a confidence level of .99
C) small n and a confidence level of .95
D) small n and a confidence level of .99

E) None of the above
F) A) and C)

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Confidence intervals are generally to be preferred over point estimates because confidence intervals


A) have a firmer statistical basis
B) result in greater precision
C) account for sampling error
D) are based on more degrees of freedom

E) All of the above
F) None of the above

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The national norm for third graders on a standardized test of reading achievement is a score of 27. Mrs. Johnson obtains the mean score on the test for a random sampling of third graders from her school district. The results for Mrs. Johnson's sample are X‾=33.1,sX=5.2andn=30\overline{X} = 33.1, s_X = 5.2 and n=30 (a) Construct the 95% confidence interval for her population mean score. (b) Construct the 99% confidence interval for her population mean score. (c) What generalization is illustrated by a comparison of the answers to (a) and (b)?

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(a)
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(b)
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(c...

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The following are the achievement test results for 15 matched pairs taught by Method A and Method B. The following are the achievement test results for 15 matched pairs taught by Method A and Method B. (a)Construct the 95% confidence interval for (\mu_A - \mu_B) . (b)Ignore thecorrelation coefficient and treat the two samples as though they were independent. Construct the 95% confidence interval for (\mu_A - \mu_B) . (c)What does a comparison of the answers to (a) and (b) suggest concerning the effect on interval estimates of using samples? (a)Construct the 95% confidence interval for (μA−μB)(\mu_A - \mu_B) . (b)Ignore thecorrelation coefficient and treat the two samples as though they were independent. Construct the 95% confidence interval for (μA−μB)(\mu_A - \mu_B) . (c)What does a comparison of the answers to (a) and (b) suggest concerning the effect on interval estimates of using samples?

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(a)
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(b)
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(c) dependent...

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A random sample of 20 students at Alpha College is asked how many hours a week they study on the average. The following are the results: A random sample of 20 students at Alpha College is asked how many hours a week they study on the average. The following are the results: and Construct the 95% confidence interval for the mean hours studied per week for the entire student body. What does the 95% refer to? Be very explicit and precise in your answer. and A random sample of 20 students at Alpha College is asked how many hours a week they study on the average. The following are the results: and Construct the 95% confidence interval for the mean hours studied per week for the entire student body. What does the 95% refer to? Be very explicit and precise in your answer. Construct the 95% confidence interval for the mean hours studied per week for the entire student body. What does the 95% refer to? Be very explicit and precise in your answer.

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If the study were repeated m...

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Suppose a 95% confidence interval for Suppose a 95% confidence interval for runs from -10 to -2. It appears likely that A) B) C) D) none of the above runs from -10 to -2. It appears likely that


A) Suppose a 95% confidence interval for runs from -10 to -2. It appears likely that A) B) C) D) none of the above
B) Suppose a 95% confidence interval for runs from -10 to -2. It appears likely that A) B) C) D) none of the above
C) Suppose a 95% confidence interval for runs from -10 to -2. It appears likely that A) B) C) D) none of the above
D) none of the above

E) A) and C)
F) All of the above

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B

For a confidence interval of For a confidence interval of , an interval of lesser width results A) when n is smaller B) when is larger C) when a larger value of C (the confidence coefficient) is required D) in none of the above circumstances , an interval of lesser width results


A) when n is smaller
B) when For a confidence interval of , an interval of lesser width results A) when n is smaller B) when is larger C) when a larger value of C (the confidence coefficient) is required D) in none of the above circumstances is larger
C) when a larger value of C (the confidence coefficient) is required
D) in none of the above circumstances

E) None of the above
F) All of the above

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The advantage of expressing a confidence interval in terms of the number of standard deviations of the variable is that


A) it is more precise
B) normal curve theory will then apply
C) it compensates for the fact that the importance of a given interscore distance depends on the size of the standard deviation of the variable
D) all of the above will occur

E) A) and D)
F) B) and C)

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Suppose a 95% confidence interval for Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known runs from 48 to 56. If we had tested Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known against Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known using Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known we would


A) have rejected Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known
B) have retained Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known
C) not be able to decide about Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known unless n were known
D) not be able to decide about Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known unless n and Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would A) have rejected B) have retained C) not be able to decide about unless n were known D) not be able to decide about unless n and were known were known

E) A) and D)
F) A) and B)

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B

Random samples are selected and the 95% confidence interval for Random samples are selected and the 95% confidence interval for is constructed. It runs from -3.1 to 9.4. (a) If a two-tailed test were used at would a significant difference be found between and Explain. (b) Give the 95% confidence interval for is constructed. It runs from -3.1 to 9.4. (a) If a two-tailed test were used at Random samples are selected and the 95% confidence interval for is constructed. It runs from -3.1 to 9.4. (a) If a two-tailed test were used at would a significant difference be found between and Explain. (b) Give the 95% confidence interval for would a significant difference be found between Random samples are selected and the 95% confidence interval for is constructed. It runs from -3.1 to 9.4. (a) If a two-tailed test were used at would a significant difference be found between and Explain. (b) Give the 95% confidence interval for and Random samples are selected and the 95% confidence interval for is constructed. It runs from -3.1 to 9.4. (a) If a two-tailed test were used at would a significant difference be found between and Explain. (b) Give the 95% confidence interval for Explain. (b) Give the 95% confidence interval for Random samples are selected and the 95% confidence interval for is constructed. It runs from -3.1 to 9.4. (a) If a two-tailed test were used at would a significant difference be found between and Explain. (b) Give the 95% confidence interval for

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(a) no; a difference of 0 fall...

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Suppose a 95% confidence interval for Suppose a 95% confidence interval for runs from -5 to +2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information runs from -5 to +2. If Suppose a 95% confidence interval for runs from -5 to +2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information were tested against a two-tailed alternative hypothesis using Suppose a 95% confidence interval for runs from -5 to +2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information our decision about Suppose a 95% confidence interval for runs from -5 to +2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information


A) is uncertain
B) should be to reject Suppose a 95% confidence interval for runs from -5 to +2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information
C) should be to retain Suppose a 95% confidence interval for runs from -5 to +2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information
D) cannot be determined without further information

E) C) and D)
F) A) and B)

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C

Which statement, if any, is incorrect?


A) confidence intervals are preferred over point estimation because they are more likely to be correct
B) the population value to be estimated does not vary, but confidence intervals made from different samples will vary
C) once a confidence interval is constructed, it is no longer proper to speak of the probability that it includes the population value
D) all of the above are true

E) A) and C)
F) B) and C)

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If we wish to estimate If we wish to estimate or within given limits, the required sample size will be related to A) the magnitude of the standard deviation(s) B) the confidence coefficient C) both of the above D) neither of the above or If we wish to estimate or within given limits, the required sample size will be related to A) the magnitude of the standard deviation(s) B) the confidence coefficient C) both of the above D) neither of the above within given limits, the required sample size will be related to


A) the magnitude of the standard deviation(s)
B) the confidence coefficient
C) both of the above
D) neither of the above

E) A) and D)
F) A) and C)

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Suppose a 95% confidence interval for Suppose a 95% confidence interval for runs from -10 to -2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information runs from -10 to -2. If Suppose a 95% confidence interval for runs from -10 to -2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information were tested against a two-tailed alternative hypothesis using Suppose a 95% confidence interval for runs from -10 to -2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information our decision about Suppose a 95% confidence interval for runs from -10 to -2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information


A) is uncertain
B) should be to reject Suppose a 95% confidence interval for runs from -10 to -2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information
C) should be to retain Suppose a 95% confidence interval for runs from -10 to -2. If were tested against a two-tailed alternative hypothesis using our decision about A) is uncertain B) should be to reject C) should be to retain D) cannot be determined without further information
D) cannot be determined without further information

E) None of the above
F) All of the above

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In establishing a confidence interval for the difference between two means, selecting a confidence level of .95 rather than a confidence level of .90 implies that


A) we can be less sure that the interval contains the true difference
B) the interval will be wider
C) the difference between the two sample means will be less
D) the difference between the two population means will be greater

E) B) and C)
F) A) and D)

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A 95% confidence interval for A 95% confidence interval for is computed for sample results. The interval runs from -.75 to +.25. This suggests that A) is probably negative B) a small sample was used C) a computational error was made D) r is significant is computed for sample results. The interval runs from -.75 to +.25. This suggests that


A) A 95% confidence interval for is computed for sample results. The interval runs from -.75 to +.25. This suggests that A) is probably negative B) a small sample was used C) a computational error was made D) r is significant is probably negative
B) a small sample was used
C) a computational error was made
D) r is significant

E) B) and D)
F) B) and C)

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The rule for constructing a confidence interval of the difference between two means is


A) The rule for constructing a confidence interval of the difference between two means is A) B) C) D)
B) The rule for constructing a confidence interval of the difference between two means is A) B) C) D)
C) The rule for constructing a confidence interval of the difference between two means is A) B) C) D)
D) The rule for constructing a confidence interval of the difference between two means is A) B) C) D)

E) None of the above
F) A) and C)

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Confidence intervals of a parameter are preferred over hypothesis testing when


A) great accuracy is required
B) logic does not point to a possible value of the parameter that is of special interest
C) we know the parameter's value and wish to predict sample outcomes
D) sampling is not random

E) B) and C)
F) A) and D)

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