ChaPTER 9 Estimation from sample data to accompany Introduction to business statistics fourth edition by ronald M. Weiers Presentation by priscilla chaffe-Stengel Donald n. Stengel o The Wadsworth Group
CHAPTER 9 Estimation from Sample Data to accompany Introduction to Business Statistics fourth edition, by Ronald M. Weiers Presentation by Priscilla Chaffe-Stengel Donald N. Stengel © 2002 The Wadsworth Group
l Chapter 9- Learning objectives Explain the difference between a point and an interval estimate Construct and interpret confidence intervals. with a z for the population mean or proportion with a t for the population mean Determine appropriate sample size to achieve specified levels of accuracy and confidence o 2002 The Wadsworth Group
Chapter 9 - Learning Objectives • Explain the difference between a point and an interval estimate. • Construct and interpret confidence intervals: – with a z for the population mean or proportion. – with a t for the population mean. • Determine appropriate sample size to achieve specified levels of accuracy and confidence. © 2002 The Wadsworth Group
ll Chapter 9-Key terms ● Unbiased estimator· Confidence level Point estimates Accuracy Interval estimates Degrees of ● Interval limits freedom(df Confidence ° Maximum likely coefficient sampling error o 2002 The Wadsworth Group
Chapter 9 - Key Terms • Unbiased estimator • Point estimates • Interval estimates • Interval limits • Confidence coefficient • Confidence level • Accuracy • Degrees of freedom (df) • Maximum likely sampling error © 2002 The Wadsworth Group
LI Unbiased point estimates Population Sample Parameter Statistic Formula o mean, X x 2=2 n-x 2 Variance, o 12 Proportion,兀 p=x Successes n trials o 2002 The Wadsworth Group
Unbiased Point Estimates Population Sample Parameter Statistic Formula • Mean, µ • Variance, s 2 • Proportion, p x x = x i n –1 ( – )2 2 2 n x i x s s = p p = x successes n trials © 2002 The Wadsworth Group
l Confidence Interval: u, o Known where x= sample mean ASSUMPTION: o=population standard infinite population deviation n= sample size z= standard normal score for area in tail=a/2 /2 O/2 z x+z o 2002 The Wadsworth Group
Confidence Interval: µ, s Known where = sample mean ASSUMPTION: s = population standard infinite population deviation n = sample size z = standard normal score for area in tail = a/2 a 2 −a a 2 n x x z n x x z z z z s ×s × + + : – : – 0 x © 2002 The Wadsworth Group