19.01.2015 Views

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

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

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

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Frequency<br />

̅<br />

Histogram of TV's Owned<br />

25<br />

20<br />

15<br />

10<br />

5<br />

0<br />

0 1 2 3 4 5 6<br />

Number of TV's<br />

2.4.8 Outlier Detection<br />

After analyz<strong>in</strong>g a dataset, how do we assess likely values <strong>for</strong> data and deem other values as<br />

outliers<br />

One approach is to determ<strong>in</strong>e how many standard deviations above (positive value) or below the<br />

mean (negative value) a given data value is.<br />

For <strong>in</strong>stance, suppose we have a dataset with mean 20 and standard deviation 3. We have an<br />

observation of 14. In terms of units, this value is 6 units below the mean. Thus, it has a deviation<br />

of -6. This deviation tells us that the data value <strong>in</strong> question is 2 standard deviations below the<br />

mean, s<strong>in</strong>ce:<br />

This measure is often called a z-score. Let‟s recap:<br />

-Score<br />

A -score tells us the number of standard deviations a data po<strong>in</strong>t, , is from its mean, ̅.<br />

Mathematically,<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 77

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!