Question 1

What is the margin of error? Explain how to interpret a "10% margin of error."

Accepted Answer

Margin of error is half of a confidence interval, converted into a percentage of the value being estimated. A 10% margin of error means that product of the critical z or t and the standard error is 10% of the mean. For example, if the mean was 10, the margin of error would be 1 point -if we were to assume 10 to be the population mean, 95% of sample means would fall between 9 and 11.

Question 2

When n > 10, the z-distribution and t-distribution are very similar.

Accepted Answer

A) True 
 B)False  False

Question 3

You randomly draw a sample of n = 25 where F1F1F1S1F1F1F10F1F1F1S1F1F1F10 = 100. If the sample mean is 10, which of the following are the bounds of a 95% confidence interval?

Accepted Answer

A)  6.08, 13.92 
B)  -29.2, 49.2 
C)  -49.2, 29.2 
D)  -38.2, 40.2 
A)  6.08, 13.92 
B)  -29.2, 49.2 
C)  -49.2, 29.2 
D)  -38.2, 40.2 A

Question 4

You should use a 95% confidence level because it is the most accurate level.

Accepted Answer

A) True 
 B)False

Question 5

You randomly draw a sample of n = 12 where F1F1F1S1F1F1F10F1F1F1S1F1F1F10 = 15. If the sample mean is -25, which of the following are the bounds of a 95% confidence interval?

Accepted Answer

A)  -27.44, -22.56 
B)  -34.43, -15.56 
C)  -27.46, -22.54 
D)  -34.53, -15.47 
A)  -27.44, -22.56 
B)  -34.43, -15.56 
C)  -27.46, -22.54 
D)  -34.53, -15.47

Question 6

You should use a 100% confidence level because it is the most comprehensive.

Accepted Answer

A) True 
 B)False

Question 7

Point estimates provide a perfect representation of a population parameter.

Accepted Answer

A) True 
 B)False

Question 8

A 99% interval will always be wider than a 95% interval.

Accepted Answer

A) True 
 B)False

Question 9

When calculating the confidence interval, if the population standard deviation is not known, it is replaced in the confidence interval boundary formula with ______.

Accepted Answer

A)  the sample range 
B)  the sample standard deviation 
C)  n - 1 
D)  A confidence interval should not be computed if the population standard deviation is unknown. 
A)  the sample range 
B)  the sample standard deviation 
C)  n - 1 
D)  A confidence interval should not be computed if the population standard deviation is unknown.

Question 10

Which of the following situations would provide the most accurate estimate of F1F1F1S1F1F1F10?

Accepted Answer

A)  n = 10; s = 50 
B)  n = 10; s = 5 
C)  n = 100; s = 50 
D)  n = 100; s = 5 
A)  n = 10; s = 50 
B)  n = 10; s = 5 
C)  n = 100; s = 50 
D)  n = 100; s = 5

Question 11

A single "best guess" from a sample as an estimate of a parameter is a ______.

Accepted Answer

A)  interval estimate 
B)  confidence interval 
C)  point estimate 
D)  point interval 
A)  interval estimate 
B)  confidence interval 
C)  point estimate 
D)  point interval

Question 12

You randomly select a sample of n = 30. What are the degrees of freedom associated with a confidence interval of the mean?

Accepted Answer

A)  30 
B)  29 
C)  28 
D)  none of these 
A)  30 
B)  29 
C)  28 
D)  none of these

Question 13

You cannot calculate a confidence interval if you do not know the population standard deviation.

Accepted Answer

A) True 
 B)False

Question 14

If you randomly select a sample of n = 16 where F1F1F1S1F1F1F10 = 4 and x̄ = 5, the boundaries of your confidence interval should be 3.04 and 6.96.

Accepted Answer

A) True 
 B)False

Question 15

You randomly draw a sample of n = 25 from a population where F1F1F1S1F1F1F10 = 3. Which is the appropriate formula for the bounds of a 95% confidence interval?

Accepted Answer

A)  $ \bar{x} \pm 1.960 * 0.6 $ 
B)  $ \bar{x} \pm 1.645 * 0.6 $ 
C)  $ \bar{x} \pm 1.960 * 0.12 $ 
D)  $ \bar{x} \pm 1.645 * 0.12 $ 
A)  $ \bar{x} \pm 1.960 * 0.6 $ 
B)  $ \bar{x} \pm 1.645 * 0.6 $ 
C)  $ \bar{x} \pm 1.960 * 0.12 $ 
D)  $ \bar{x} \pm 1.645 * 0.12 $

Question 16

Given a 95% confidence interval, you would expect 5% of sample means to be above the interval's upper bound.

Accepted Answer

A) True 
 B)False

Question 17

For the dataset below, the Director of HR is interested in determining if her most aggressive employees are the ones with the highest salaries. To test this, she collected weekly salary information from business records and gave an aggression survey to current employees. The test manual for the aggression survey contains normative information: worldwide, the mean score on the aggression survey is a 3.1 and the standard deviation is 1.
 $\begin{array}{|c|c|}
\hline \text { Weekly salary (euros) } & \text { Aggression survey } \
\hline 518 & 2 \
\hline 460 & 4 \
\hline 439 & 3 \
\hline 632 & 2 \
\hline 316 & 3 \
\hline 439 & 3 \
\hline 623 & 3 \
\hline 420 & 3 \
\hline 404 & 3 \
\hline 481 & 3\
\hline
\end{array}$ a) Compute a point estimate of the Salary variable above.
b) Compute an interval estimate of the Salary variable above. Report the critical z or t used.
c) Compute a point estimate of the Survey variable above.
d) Compute an interval estimate of the Survey variable above. Report the critical z or t used.

Accepted Answer

a) 473.20 b) CI_.95 = [4

Question 18

A researcher has identified in the average salary for a sample of his employees. If he wants to make general conclusions about the population of employees, what is that average salary?

Accepted Answer

A)  point estimate 
B)  confidence interval 
C)  interval estimate 
D)  point interval 
A)  point estimate 
B)  confidence interval 
C)  interval estimate 
D)  point interval

Question 19

When calculating a confidence interval, you find a lower bound of 10 and an upper bound of 15. Choose the correct interpretation of this interval.

Accepted Answer

A)  95% of samples of the same size drawn from the population will fall beyond 10 and 15. 
B)  95% of samples of the same size drawn from the population will fall between 10 and 15. 
C)  There is a 95% chance that the population mean is between 10 and 15. 
D)  There is a 95% chance that our sample mean accurately represents the population mean. 
A)  95% of samples of the same size drawn from the population will fall beyond 10 and 15. 
B)  95% of samples of the same size drawn from the population will fall between 10 and 15. 
C)  There is a 95% chance that the population mean is between 10 and 15. 
D)  There is a 95% chance that our sample mean accurately represents the population mean.

Question 20

You randomly draw a sample of n = 16 where F1F1F1S1F1F1F10 = 4. If the sample mean is 1, which of the following are the bounds of a 95% confidence interval?

Accepted Answer

A)  -2.96, .96 
B)  -.96, 2.96 
C)  -14.68, 16.68 
D)  -16.68, 14.68 
A)  -2.96, .96 
B)  -.96, 2.96 
C)  -14.68, 16.68 
D)  -16.68, 14.68

What is the margin of error? Explain how to interpret a "10% margin of error."

When n > 10, the z-distribution and t-distribution are very similar.

You randomly draw a sample of n = 25 where ^ = 100. If the sample mean is 10, which of the following are the bounds of a 95% confidence interval?

You should use a 95% confidence level because it is the most accurate level.

You randomly draw a sample of n = 12 where ^ = 15. If the sample mean is -25, which of the following are the bounds of a 95% confidence interval?

You should use a 100% confidence level because it is the most comprehensive.

Point estimates provide a perfect representation of a population parameter.

A 99% interval will always be wider than a 95% interval.

When calculating the confidence interval, if the population standard deviation is not known, it is replaced in the confidence interval boundary formula with ______.

Which of the following situations would provide the most accurate estimate of ?

A single "best guess" from a sample as an estimate of a parameter is a ______.

You randomly select a sample of n = 30. What are the degrees of freedom associated with a confidence interval of the mean?

You cannot calculate a confidence interval if you do not know the population standard deviation.

If you randomly select a sample of n = 16 where  = 4 and x̄ = 5, the boundaries of your confidence interval should be 3.04 and 6.96.

You randomly draw a sample of n = 25 from a population where  = 3. Which is the appropriate formula for the bounds of a 95% confidence interval?

Given a 95% confidence interval, you would expect 5% of sample means to be above the interval's upper bound.

A researcher has identified in the average salary for a sample of his employees. If he wants to make general conclusions about the population of employees, what is that average salary?

When calculating a confidence interval, you find a lower bound of 10 and an upper bound of 15. Choose the correct interpretation of this interval.

You randomly draw a sample of n = 16 where  = 4. If the sample mean is 1, which of the following are the bounds of a 95% confidence interval?

The Language of Statistics

Working With Numbers and Data Display

Central Tendency and Variability

Probability Distributions

Sampling Distributions

Hypothesis Testing

Tests for Significance: Z-Tests and One-Sample T-Tests

Tests for Significance: Paired and Independent-Samples T-Test

Analysis of Variance Anova

CHI-Squared Tests of Fit

Correlation R and Regression Y BX A

Matching Statistical Tests to Business Problems

Filters

Exam 6: Estimation and Confidence Intervals

What is the margin of error? Explain how to interpret a "10% margin of error."

When n > 10, the z-distribution and t-distribution are very similar.

You randomly draw a sample of n = 25 where  = 100. If the sample mean is 10, which of the following are the bounds of a 95% confidence interval?

You should use a 95% confidence level because it is the most accurate level.

You randomly draw a sample of n = 12 where  = 15. If the sample mean is -25, which of the following are the bounds of a 95% confidence interval?

You should use a 100% confidence level because it is the most comprehensive.

Point estimates provide a perfect representation of a population parameter.

A 99% interval will always be wider than a 95% interval.

When calculating the confidence interval, if the population standard deviation is not known, it is replaced in the confidence interval boundary formula with ______.

Which of the following situations would provide the most accurate estimate of ?

A single "best guess" from a sample as an estimate of a parameter is a ______.

You randomly select a sample of n = 30. What are the degrees of freedom associated with a confidence interval of the mean?

You cannot calculate a confidence interval if you do not know the population standard deviation.

If you randomly select a sample of n = 16 where  = 4 and x̄ = 5, the boundaries of your confidence interval should be 3.04 and 6.96.

You randomly draw a sample of n = 25 from a population where  = 3. Which is the appropriate formula for the bounds of a 95% confidence interval?

Given a 95% confidence interval, you would expect 5% of sample means to be above the interval's upper bound.

A researcher has identified in the average salary for a sample of his employees. If he wants to make general conclusions about the population of employees, what is that average salary?

When calculating a confidence interval, you find a lower bound of 10 and an upper bound of 15. Choose the correct interpretation of this interval.

You randomly draw a sample of n = 16 where  = 4. If the sample mean is 1, which of the following are the bounds of a 95% confidence interval?

The Language of Statistics

Working With Numbers and Data Display

Central Tendency and Variability

Probability Distributions

Sampling Distributions

Hypothesis Testing

Tests for Significance: Z-Tests and One-Sample T-Tests

Tests for Significance: Paired and Independent-Samples T-Test

Analysis of Variance Anova

CHI-Squared Tests of Fit

Correlation R and Regression Y BX A

Matching Statistical Tests to Business Problems

Filters

You randomly draw a sample of n = 25 where ^ = 100. If the sample mean is 10, which of the following are the bounds of a 95% confidence interval?

You randomly draw a sample of n = 12 where ^ = 15. If the sample mean is -25, which of the following are the bounds of a 95% confidence interval?