Re: margin of error

[dennis roberts]

rich ... i really don't want to spend my time arguing with you about my little handout made for my class that i shared with folks IF they thought they could get some benefit out of it ...

but, i did take the basic notion, which i think is good, from moore and mccabe's (which i acknowledged) "intro to the practice of statistics" 3rd edition ... which says in at least two places:

p443 ... " ... the confidence interval for a population mean will have a specified margin of error (m) when the sample size is ... "

and then uses the formula that i put in the handout ... though, here they make an assumption of the population SD and DO use z ... rather than t that i used

p506 ... when they talk about the SAME notion of CIs ... but, in the case when we don't know the SD ... and use the sample estimator for it ... they talk about a t confidence interval and further say: " ... so the margin of error (m) for the population mean when we use t that data to estimate mu is t * (s/sqrt n) ... "

t is what would be necessary for building a regular kind of 95% (or other) CI

if you want to argue with moore and/or mccabe ... that's fine ... but, i have not heard anyone on this list ... really argue vociferously that what THEY did ... was in error along the lines you have been fussing with my handout about ...

have a good day


.
.
=================================================================
Instructions for joining and leaving this list, remarks about the
problem of INAPPROPRIATE MESSAGES, and archives are available at:
. http://jse.stat.ncsu.edu/ .
=================================================================