Question 1

In the formula for a confidence interval for μ,1 − α is called the ____________________.

Accepted Answer

The answer of In the formula for a confidence interval...

Question 2

An unbiased estimator is ____________________ if its variance gets smaller as n gets larger.

Accepted Answer

The answer of An unbiased estimator is ____________________ if its...

Question 3

An unbiased estimator of a population parameter is defined as:

Accepted Answer

A) an estimator whose expected value is equal to the parameter. 
B) an estimator whose variance is equal to one. 
C) an estimator whose expected value is equal to zero. 
D) an estimator whose variance goes to zero as the sample size goes to infinity. 
A) an estimator whose expected value is equal to the parameter. 
B) an estimator whose variance is equal to one. 
C) an estimator whose expected value is equal to zero. 
D) an estimator whose variance goes to zero as the sample size goes to infinity.

Question 4

The confidence interval estimate of the population mean is constructed around the sample mean.

Accepted Answer

A) True 
 B)False

Question 5

In the formula   ,the subscript α / 2 refers to the area in the lower tail or upper tail of the sampling distribution of the sample mean.

Accepted Answer

A) True 
 B)False

Question 6

Suppose a sample size of 5 has mean 9.60.If the population variance is 5 and the population is normally distributed,the lower limit for a 92% confidence interval is 7.85.

Accepted Answer

A) True 
 B)False

Question 7

The sample size needed to estimate the population mean was found to be 865.If the value of the population standard deviation was 75,and the maximum allowable error was 5,then the confidence level used was 95%.

Accepted Answer

A) True 
 B)False

Question 8

A precision control engineer is interested in the mean length of tubing being cut automatically by machine.It is known that the standard deviation in the cutting length is 0.15 feet.A sample of 60 cut tubes yields a mean length of 12.15 feet.This sample will be used to obtain a 99% confidence interval for the mean length cut by machine.
a.What is the zα / 2 value to use in obtaining the confidence interval?
b.Develop the 99% confidence interval for μ.

Accepted Answer

a. zα_{/ 2} = 2.58 b. LCL

Question 9

Explain briefly why interval estimators are preferred to point estimators.

Accepted Answer

An interval estimator incorpor

Question 10

____________________ estimators reflect the effects of larger sample sizes,but ____________________ estimators do not.

Accepted Answer

The answer of ____________________ estimators reflect the effects of larger...

Question 11

The sample size needed to estimate a population mean to within 10 units was found to be 68.If the population standard deviation was 50,then the confidence level used was:

Accepted Answer

A) 99% 
B) 95% 
C) 90% 
D) None of these choices. 
A) 99% 
B) 95% 
C) 90% 
D) None of these choices.

Question 12

Time Spent Playing Computer Games 
Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. ​ ​
-{Time Spent Playing Computer Games Narrative} Determine the 95% confidence interval estimate of the population mean if the sample mean is changed to 8.5 hours.

Accepted Answer

LCL = 8.21

Question 13

A(n)____________________ estimator of a population parameter is an estimator whose expected value is equal to that parameter.

Accepted Answer

The answer of A(n)____________________ estimator of a population parameter is...

Question 14

The sample proportion   is a consistent estimator of the population proportion p because it is unbiased and the variance of   is p(1 − p)/ n,which grows smaller as n grows larger.

Accepted Answer

A) True 
 B)False

Question 15

Define consistency.

Accepted Answer

An unbiased estimator is said

Question 16

The term 1 − α refers to the probability that a confidence interval does not contain the population parameter.

Accepted Answer

A) True 
 B)False

Question 17

Increasing the sample size fourfold decreases the width of the confidence interval by ____________________.

Accepted Answer

The answer of Increasing the sample size fourfold decreases the...

Question 18

College Dean
 A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. ​ ​
-{College Dean Narrative} What sample size should be used if we wish to estimate the population mean to within 10 units?

Accepted Answer

n = 2,663

Question 19

An unbiased estimator is said to be consistent if the difference between the estimator and the parameter grows larger as the sample size grows larger.

Accepted Answer

A) True 
 B)False

Question 20

As the bound on the error of estimation decreases,the sample size ____________________.

Accepted Answer

The answer of As the bound on the error of...

Exam 10: Introduction to Estimation

In the formula for a confidence interval for μ,1 − α is called the ____________________.

An unbiased estimator is ____________________ if its variance gets smaller as n gets larger.

An unbiased estimator of a population parameter is defined as:

The confidence interval estimate of the population mean is constructed around the sample mean.

In the formula ,the subscript α / 2 refers to the area in the lower tail or upper tail of the sampling distribution of the sample mean.

Suppose a sample size of 5 has mean 9.60.If the population variance is 5 and the population is normally distributed,the lower limit for a 92% confidence interval is 7.85.

The sample size needed to estimate the population mean was found to be 865.If the value of the population standard deviation was 75,and the maximum allowable error was 5,then the confidence level used was 95%.

Explain briefly why interval estimators are preferred to point estimators.

____________________ estimators reflect the effects of larger sample sizes,but ____________________ estimators do not.

The sample size needed to estimate a population mean to within 10 units was found to be 68.If the population standard deviation was 50,then the confidence level used was:

A(n)____________________ estimator of a population parameter is an estimator whose expected value is equal to that parameter.

The sample proportion is a consistent estimator of the population proportion p because it is unbiased and the variance of is p(1 − p)/ n,which grows smaller as n grows larger.

Define consistency.

The term 1 − α refers to the probability that a confidence interval does not contain the population parameter.

Increasing the sample size fourfold decreases the width of the confidence interval by ____________________.

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. ​ ​ -{College Dean Narrative} What sample size should be used if we wish to estimate the population mean to within 10 units?

An unbiased estimator is said to be consistent if the difference between the estimator and the parameter grows larger as the sample size grows larger.

As the bound on the error of estimation decreases,the sample size ____________________.

What Is Statistics

Graphical Descriptive Techniques 1

Graphical Descriptive Techniques 2

Numerical Descriptive Techniques

Data Collection and Sampling

Probability

Random Variables and Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions

Introduction to Hypothesis Testing

Inference About a Population

Inference About Comparing Two Populations

Analysis of Variance

Chi-Squared Tests

Simple Linear Regression and Correlation

Multiple Regression

Model Building

Nonparametric Statistics

Time-Series Analytics and Forecasting

Statistical Process Control

Decision Analysis

Conclusion

Filters

estimators reflect the effects of larger sample sizes,but estimators do not.

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. -{College Dean Narrative} What sample size should be used if we wish to estimate the population mean to within 10 units?