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Statistics for Decision- Making in Business - Maricopa Community ...

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Where is the number of standard deviations endpo<strong>in</strong>ts <strong>for</strong> a confidence<br />

<strong>in</strong>terval with total area <strong>in</strong> the tails. i.e.<br />

Us<strong>in</strong>g this “crash course” <strong>in</strong> theoretical confidence <strong>in</strong>terval-f<strong>in</strong>d<strong>in</strong>g, compute the<br />

95% confidence us<strong>in</strong>g these ideas. Do you get a similar result How close<br />

6.3 Confidence Interval <strong>for</strong> ̂<br />

6.3.1 Confidence Interval <strong>for</strong> ̂ Us<strong>in</strong>g Sampl<strong>in</strong>g Distributions<br />

Suppose that it is of <strong>in</strong>terest to estimate the proportion of recent customers that say they would<br />

come back and shop at your store. You take a sample and determ<strong>in</strong>e that, of 30 people, 20 said<br />

they would and 10 said they wouldn‟t. You would like to make an <strong>in</strong>ference about the population<br />

of all of your customers. In your sample, you know that:<br />

Is the proportion of your customers that will come back and purchase from you aga<strong>in</strong>. You are<br />

look<strong>in</strong>g to f<strong>in</strong>d a confidence <strong>in</strong>terval <strong>for</strong> ̂. How do we do that with the simulator if we have no<br />

data<br />

In reality, we do. We just have to make it numerical. In reality, 20/30 is an average. It is the<br />

average of 30 responses. If we let:<br />

<strong>Statistics</strong> <strong>for</strong> <strong>Decision</strong>-<strong>Mak<strong>in</strong>g</strong> <strong>in</strong> Bus<strong>in</strong>ess © Milos Podmanik Page 202

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