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

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Chapter 2<br />

Visual Representations of Data<br />

2.1 Visualiz<strong>in</strong>g Categorical Data<br />

When summariz<strong>in</strong>g data, it goes without say that there are appropriate and <strong>in</strong>appropriate ways to<br />

display the data. For example, if you collected a person‟s age and <strong>in</strong>come, you might be<br />

<strong>in</strong>terested <strong>in</strong> study<strong>in</strong>g <strong>in</strong>come as a function of age. In this case, you probably would not want to<br />

build a pie chart, s<strong>in</strong>ce you‟re study<strong>in</strong>g quantitative variables (two of them, at that).<br />

In the previous chapter, the ma<strong>in</strong> types of categorical data visualizations were mentioned – bar<br />

graphs and pie charts. Our aim here is simply to summarize and to show how to use them <strong>in</strong><br />

conjunction with Excel. We‟ll create three types of representations:<br />

<br />

<br />

<br />

Pie Chart<br />

Frequency Bar Graph – Vertical axis keeps tracks the number of <strong>in</strong>stances of each<br />

observation<br />

Relative Frequency Bar Graph – Vertical axis keeps tracks the ratio of <strong>in</strong>stances of each<br />

observation (decimal or percentage, typically)<br />

2.1.1 Creat<strong>in</strong>g a Pie Chart Us<strong>in</strong>g Excel<br />

Suppose a hotel owner asks 20 randomly selected recent guests to respond to the follow<strong>in</strong>g<br />

statement regard<strong>in</strong>g their experiences at the new hotel lounge:<br />

“The d<strong>in</strong><strong>in</strong>g experience <strong>in</strong> Harlan’s Hotel Lounge is worth revisit<strong>in</strong>g.”<br />

Respondents circle one of the follow<strong>in</strong>g letter comb<strong>in</strong>ations:<br />

- SD - Strongly Disagree<br />

- D -Disagree<br />

- A - Agree<br />

- SA - Strongly Agree<br />

The result<strong>in</strong>g data is shown below:<br />

Participant 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20<br />

Op<strong>in</strong>ion D A SD A SD SA A A A A A A D A A A A A A A<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 29

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