), we need to minimize.24nA+.24nB.This is 0.163 for choice (1) and 0.107 forchoice (2). Choice (2) has smaller width.(b) By looking at the expression above, theCI width is minimized when1nA+1nBisas small as possible withnA+nB= 100.Based on part(a), the width is smaller forthe values ofnAandnBthat are closertogether.Thus the ’natural’ conjectureis that the CI width can be minimized ifnA=nB= 50. This is the correct answer.It is primarily for this reason that mostscientific studies comparing 2 (or more)groups have equal sample sizes.Grade Distribution90-99:2280-89:4170-79:26median =7960-69:1750-59:13below: 8
This is the end of the preview.
access the rest of the document.