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

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Thus, the standard deviation would be √<br />

, mean<strong>in</strong>g that, on average, we would<br />

expect the die value to deviate by 1.708, or nearly 2 units from the average (1.5 to 5.5, which is<br />

pretty much 1 to 6).<br />

Thus, we have that:<br />

In reality, keep <strong>in</strong> m<strong>in</strong>d that we would often not know much about our population. We get the<br />

luxury of study<strong>in</strong>g someth<strong>in</strong>g we can fully expla<strong>in</strong>. This is all <strong>in</strong> an ef<strong>for</strong>t to better understand<br />

sampl<strong>in</strong>g distributions.<br />

Suppose we conducted an experiment of roll<strong>in</strong>g the die 10 times. For one random sequence, we<br />

might obta<strong>in</strong> the follow<strong>in</strong>g result:<br />

4 6<br />

3 4<br />

4 1<br />

3 4<br />

1 2<br />

Not surpris<strong>in</strong>gly, we get a fairly even spread of values 1 – 6. If we are to compute the average,<br />

we would obta<strong>in</strong> 3.2. That is if all rolls came up as the same number, each roll would be 3.2.<br />

Suppose we asked 19 other people to roll a die 10 times and to then report back to us the mean.<br />

Here is what we might f<strong>in</strong>d (based on a computer simulation of rolls):<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 183

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