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Chapter 14

# SOAN 3120 Chapter Notes - Chapter 14: Confidence Interval, Sampling Distribution, Standard Deviation

by OC789840

School

University of GuelphDepartment

Sociology and AnthropologyCourse Code

SOAN 3120Professor

Andrew HathawayChapter

14This

**preview**shows half of the first page. to view the full**1 pages of the document.**Chapter 14-Condence Intervals:

Statistical Inference:

Provides methods for drawing conclusions about a population from sample

data

Simple conditions for inference about a mean:

oWe have an SRS from the population of interest. This is no nonresponse

or other practical diculty

oThe variable we measure has an exactly normal distribution

N(mu,sigma) in the population

oWe don’t know the population mean, but we do know the population

standard deviation

The Reasoning of Statistical Estimation:

Sampling distribution of XBAR tells us how close to mu the sample mean is

likely to be

Statistical estimated just turns that information around to say how close to

XBAR the unknown population mean is likely to be

We call the interval numbers between the values con*dence intervals for mu

Margin of Error and Condence Level:

Most con*dence intervals look like: estimate (+ over -) margin of error

A level C con*dence interval for a parameter has 2 parts:

oAn interval calculated from the data in the way written above

oA con*dence level C, which gives the probability that the interval will

capture the true parameter value in repeated samples

The con*dence level is the success rate of the method that produces the

interval

We don’t know whether the 95% con*dence interval from a particular sample

is one of the 95% that capture mu or one of the unlikely 5% that miss

Condence Intervals for a Population Mean:

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