Lecture notes - inferences for two means (Part 1)

Lecture notes - inferences for two means (Part 1) - Sec 9.2...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Sec 9.2 Comparing two population means: independent sampling (large samples) 1. Independent samples Two samples are independent samples if the sample selected from one population has no effect on the sample selected from the other population. 2. Notation Population 1: µ 1 , σ 1 , n 1 , 1 x , s 1 Population 2: µ 2 , σ 2 , n 2 , 2 x , s 2 3. Case I Sampling distribution for 2 1 x x- (1) 2 1 2 1 μ μ μ- =- x x (2) 2 2 2 1 2 1 2 2 2 1 2 1 2 2 1 2 1 n n n n x x x x σ σ σ σ σ σ + = + =-- (3) If the sample sizes are large enough ( n 1 ≥30, n 2 ≥30), 2 1 x x- is approximately normally distributed. The standardized version of 2 1 x x- 2 2 2 1 2 1 2 1 2 1 2 2 2 1 2 1 2 1 2 1 ) ( ) ( n s n s x x n n x x z +--- ≈ +--- = μ μ σ σ μ μ has the standard normal distribution. 4. [Case I] Large-sample confidence interval for µ 1- µ 2 ;and test of hypothesis conditions for Case I (1) indep samples (2) large samples (or normal populations, and known σ 1 and σ 2 ) (4a) The (1-α)100% confidence interval for µ...
View Full Document

This note was uploaded on 09/10/2009 for the course STAT 217 taught by Professor Dan during the Winter '07 term at University of Calgary.

Page1 / 3

Lecture notes - inferences for two means (Part 1) - Sec 9.2...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online