Module 4 Sampling Confidence Interval Estimation 2 
Statistics for Managers using
Microsoft Excel
6th Edition
Module 4
Sampling &
Confidence Interval Estimation
Copyright ©2012 Pearson Education
Chap 8-1
Chapter Outline
Confidence Intervals for the Population
Mean, μ
when Population Standard Deviation σ is Known when Population Standard Deviation σ is Unknown
Confidence Intervals for the Population
Proportion, p
Determining the Required Sample Size
Copyright ©2012 Pearson Education
Chap 8-2
Introduction
Copyright ©2012 Pearson Education
Estimation is the process of estimating the value of a parameter from information obtained from a sample.
Chap 8-3
Point and Interval Estimates
A point estimate is a specific numerical value of a parameter.
The best point estimate of the population mean is the sample mean.
Copyright ©2012 Pearson Education
An interval estimate of a parameter is an interval or a range of values used to estimate the parameter. This estimate may or may not contain the value of the parameter being estimated. Chap 8-4
Confidence Level and
Confidence Interval
• A 95% confidence level for μ does not mean “the probability that the interval contains μ is 0.95”. The
95% refers to the fraction of intervals, constructed in the long run from many samples of the same size that contains the parameter μ.
• Confidence Interval - An interval estimate for which there is a specified degree of certainty that the actual value of the population parameter will fall within the interval. Copyright ©2012 Pearson Education
Chap 8-5
Point and Interval Estimates
A point estimate is a single number,
a confidence interval provides additional information about the variability of the estimate
Lower
Confidence
Limit
Point Estimate
Upper
Confidence
Limit
Width of confidence interval
Copyright ©2012 Pearson Education
Chap 8-6
Point Estimates
We can estimate a
Population Parameter …
with a Sample
Statistic
(a Point Estimate)
Mean
μ
X
Proportion
p
Copyright ©2012
Microsoft Excel
6th Edition
Module 4
Sampling &
Confidence Interval Estimation
Copyright ©2012 Pearson Education
Chap 8-1
Chapter Outline
Confidence Intervals for the Population
Mean, μ
when Population Standard Deviation σ is Known when Population Standard Deviation σ is Unknown
Confidence Intervals for the Population
Proportion, p
Determining the Required Sample Size
Copyright ©2012 Pearson Education
Chap 8-2
Introduction
Copyright ©2012 Pearson Education
Estimation is the process of estimating the value of a parameter from information obtained from a sample.
Chap 8-3
Point and Interval Estimates
A point estimate is a specific numerical value of a parameter.
The best point estimate of the population mean is the sample mean.
Copyright ©2012 Pearson Education
An interval estimate of a parameter is an interval or a range of values used to estimate the parameter. This estimate may or may not contain the value of the parameter being estimated. Chap 8-4
Confidence Level and
Confidence Interval
• A 95% confidence level for μ does not mean “the probability that the interval contains μ is 0.95”. The
95% refers to the fraction of intervals, constructed in the long run from many samples of the same size that contains the parameter μ.
• Confidence Interval - An interval estimate for which there is a specified degree of certainty that the actual value of the population parameter will fall within the interval. Copyright ©2012 Pearson Education
Chap 8-5
Point and Interval Estimates
A point estimate is a single number,
a confidence interval provides additional information about the variability of the estimate
Lower
Confidence
Limit
Point Estimate
Upper
Confidence
Limit
Width of confidence interval
Copyright ©2012 Pearson Education
Chap 8-6
Point Estimates
We can estimate a
Population Parameter …
with a Sample
Statistic
(a Point Estimate)
Mean
μ
X
Proportion
p
Copyright ©2012