P 05 z2 z0025 196 220500 044 n 500 95 confidence

Info iconThis preview shows page 1. Sign up to view the full content.

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

Unformatted text preview: population of the registered voters that favour the candidate. p α=.05; zα/2 = z0.025 =1.96; = 220/500 = 0.44; n = 500 95% Confidence interval: p ± zα 2 p ( 1n− p ) 0.44 ± 1.96 0.44⋅( 1− 0.44 ) 500 Interval Estimation 0.44 ± 0.04351 0.3965 ≤ p ≤ 0.4835 Example 1 Political Science, Inc. (PSI) specializes in voter polls and surveys designed to keep political office seekers informed of their position in a race. In a current election campaign, PSI has just found that 220 registered voters, out of 500 surveyed, favour a particular candidate. PSI wants to develop a 95% confidence interval estimate for the proportion of the population of the registered voters that favour the candidate. p α=.05; zα/2 = z0.025 =1.96; = 220/500 = 0.44; n = 500 95% Confidence interval: p ± zα 2 p ( 1n− p ) 0.44 ± 1.96 0.44⋅( 1− 0.44 ) 500 Interval Estimation 0.44 ± 0.04351 0.3965 ≤ p ≤ 0.4835 Or using MS Excel: Lower: =.44– NORM.S.INV(1–.05/2)*SQRT(.44*(1–.44)/500)=0.396490565 Upper: =.44+NORM.S..NV(1–.05/2)*SQRT(.44*(1–.44)/500)=0.483509435 Example 1 Political Science, Inc. (PSI) specializes in voter polls and surveys designed to keep political office seekers informed of their position in a race. In a current election campaign, PSI has just found that 220 registered voters, out of 500 surveyed, favour a particular candidate. PSI wants to develop a...
View Full Document

This document was uploaded on 03/05/2014.

Ask a homework question - tutors are online