Question 1

Suppose a 95% confidence interval for   
 runs from 48 to 56. If we had tested 
   
 against 
   
 using 
   
 we would

Accepted Answer

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 
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

Question 2

Suppose a 95% confidence interval for  
 runs from -5 to +2. If 
 
 were tested against a two-tailed alternative hypothesis using 
   
 our decision about

Accepted Answer

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   
C)  should be to retain   
D)  cannot be determined without further information C

Question 3

Suppose a 95% confidence interval for   
 runs from -10 to -2. It appears likely that

Accepted Answer

A)    
B)    
C)    
D)  none of the above 
A)    
B)    
C)    
D)  none of the above B

Question 4

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

Accepted Answer

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 
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

Question 5

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

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 6

The practice of making confidence intervals of   
 is recommended because

Accepted Answer

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 
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

Question 7

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

Accepted Answer

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 
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

Question 8

Suppose a 95% confidence interval for   
 runs from -10 to -2. If 
  
 were tested against a two-tailed alternative hypothesis using 
   
 our decision about

Accepted Answer

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   
C)  should be to retain   
D)  cannot be determined without further information

Question 9

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?

Accepted Answer

(a) 
 @#IMG-DLM& 
(b) 
 @#IMG-DLM& 
 (c) dependent

Question 10

For a confidence interval of   
, an interval of lesser width results

Accepted Answer

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 
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

Question 11

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

Accepted Answer

(a) no; a difference of 0 fall

Question 12

Which statement, if any, is incorrect?

Accepted Answer

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 
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

Question 13

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.

Accepted Answer

@#IMG-DLM& 
If the study were repeated m

Question 14

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

Accepted Answer

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

Question 15

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?

Accepted Answer

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

Question 16

Confidence intervals of a parameter are preferred over hypothesis testing when

Accepted Answer

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 
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

Question 17

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 $\overline{X} = 33.1, s_X = 5.2 and n=30$ (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)?

Accepted Answer

(a) 
 @#IMG-DLM& 
 (b) 
 @#IMG-DLM& 
 (c

Question 18

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

Accepted Answer

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 
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

Question 19

A 95% confidence interval for   
 is computed for sample results. The interval runs from -.75 to +.25. This suggests that

Accepted Answer

A)    is probably negative 
B)  a small sample was used 
C)  a computational error was made 
D)  r is significant 
A)    is probably negative 
B)  a small sample was used 
C)  a computational error was made 
D)  r is significant

Question 20

If we wish to estimate  
 or 
  
 within given limits, the required sample size will be related to

Accepted Answer

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

Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would

Suppose a 95% confidence interval for runs from -5 to +2. If were tested against a two-tailed alternative hypothesis using our decision about

Suppose a 95% confidence interval for runs from -10 to -2. It appears likely that

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

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

The practice of making confidence intervals of is recommended because

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

Suppose a 95% confidence interval for runs from -10 to -2. If were tested against a two-tailed alternative hypothesis using our decision about

For a confidence interval of , an interval of lesser width results

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

Which statement, if any, is incorrect?

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

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?

Confidence intervals of a parameter are preferred over hypothesis testing when

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 95% confidence interval for is computed for sample results. The interval runs from -.75 to +.25. This suggests that

If we wish to estimate or within given limits, the required sample size will be related to

Introduction

Frequency Distributions, Percentiles,

Graphic Representation of Frequency Distributions

Central Tendency

Variability and Standard Z Scores

Standard Scores and the Normal Curve

Correlation

Prediction

Interpretive Aspects of Correlation and Regression

Probability

Random Sampling and Sampling Distributions

Introduction to Statistical Inference: Testing Hypotheses About Single Means Z and T

Interpreting the Results of Hypothesis Testing: Effect Size, Type I and Type II Errors, and Power

Testing Hypotheses About the Difference Between Two Independent Groups

Testing for a Difference

Inference About Correlation Coefficients

Testing for Differences Among Three or More Groups: One-Way Analysis of Variance and Some Alternatives

Factorial Analysis of Variance

Chi-Square and Inference About Frequencies

Some Almost Assumption-Free Tests

Filters

Exam 17: An Alternative to Hypothesis Testing: Confidence Intervals

Suppose a 95% confidence interval for runs from 48 to 56. If we had tested against using we would

Suppose a 95% confidence interval for runs from -5 to +2. If were tested against a two-tailed alternative hypothesis using our decision about

Suppose a 95% confidence interval for runs from -10 to -2. It appears likely that

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

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

The practice of making confidence intervals of is recommended because

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

Suppose a 95% confidence interval for runs from -10 to -2. If were tested against a two-tailed alternative hypothesis using our decision about

For a confidence interval of , an interval of lesser width results

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

Which statement, if any, is incorrect?

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

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?

Confidence intervals of a parameter are preferred over hypothesis testing when

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 95% confidence interval for is computed for sample results. The interval runs from -.75 to +.25. This suggests that

If we wish to estimate or within given limits, the required sample size will be related to

Introduction

Frequency Distributions, Percentiles,

Graphic Representation of Frequency Distributions

Central Tendency

Variability and Standard Z Scores

Standard Scores and the Normal Curve

Correlation

Prediction

Interpretive Aspects of Correlation and Regression

Probability

Random Sampling and Sampling Distributions

Introduction to Statistical Inference: Testing Hypotheses About Single Means Z and T

Interpreting the Results of Hypothesis Testing: Effect Size, Type I and Type II Errors, and Power

Testing Hypotheses About the Difference Between Two Independent Groups

Testing for a Difference

Inference About Correlation Coefficients

Testing for Differences Among Three or More Groups: One-Way Analysis of Variance and Some Alternatives

Factorial Analysis of Variance

Chi-Square and Inference About Frequencies

Some Almost Assumption-Free Tests

Filters