BUS304 – Data Presentation1 Graphs Visual presentation of data Pie Chart Bar Chart Line Chart Scatter Chart

BUS304 – Data Presentation 1

Graphs

Visual presentation of data

Pie Chart

Bar Chart

Line Chart

Scatter Chart


A good graph should

Accurately conveys the information

Grabs the reader’s attention (visually enjoyable)

Complements or demonstrates arguments presented in the text

Is simple and uncluttered

Clearly shows trends or differences in the data

Is visually accurate (i.e. one chart value is 15 and another is 30,

then 30 should be twice the size of 15)


Why use graphs?

Graphs

Are quick and direct

Highlight the most important facts

Facilitate understanding of the data

Can convince readers

Can be easily remembered.Most of the time, creating graphs is more of an art. Both visually correct data can create different

Most of the time, creating graphs is more of an art. Both visually correct data can create different


Not always good to use graphs

The data are very dispersed The data are very numerous


Not always good to use graphs

There are too few data The data show little variations

Sometimes, you may need to try different graphs, and may determine not to use graph in the end.

Sometimes, you may need to try different graphs, and may determine not to use graph in the end.


Usually present categorical and numerical variables grouped in class or intervals

Can be either horizontal of vertical

Bar chart

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1993 1994 1995 1996 1997 1998

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Title

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1993 1994 1995 1996 1997 1998

X Axis

Y A

xis

Legend

category names

values


Create a basic bar chart Open file “data2.xls” Create a bar chart using the data in sheet 1

Note that in Excel, the vertical bar chart is called “Column” Think: do you prefer vertical bars or horizontal bars?


Other Bar Charts

Side by side bars / stacked bars / 100% stacked bars when more than one piece of info in one category

Create these three charts using data from sheet 1. Compare the difference of the key information each chart conveys

Legend is important in those charts

Legend is important in those charts


Pie Chart A way of summarizing a set of categorical data Convenient to present the proportion of each category It is generally more difficult to convey the actual amount

Works especially when there are not too many categories and the proportions are significantly different from categories.


ExerciseUse the data in sheet 2 to create a Pie chart.

Compare it with the bar chart. Discuss the different information it conveys


Line Chart

Especially useful in statistics and science. To reflect the trend.

Can draw multiple lines in one graph for comparison.

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1996 1997 1998 1999 2000 2001 2002

No. of Men

No. of Women

Note: when using Excel to generate a line chart, the X-axis is stillregarded as categorical names.It does not have numerical value

Note: when using Excel to generate a line chart, the X-axis is stillregarded as categorical names.It does not have numerical value

Exercise: Sheet 1


Scatter Chart Mostly used in science and statistics to reflect the

sample location. X-axis and y-axis both have numerical values Shows data correlations (positive, negative, etc.)


Observe data correlation from scatter chart

Find the data from sheet 3.

Draw scatter chart using

Sq. Feet as x-axis, Price as y-axis

Age as x-axis, Price as y-axis

No. of bedrooms as x-axis, Price as y-axis

No. of bathrooms as x-axis, Price as y-axis

No. of garages as x-axis, Price as y-axis


Summary

4 Basic types of charts:

Bar chart

Pie chart

Line chart

Scatter chart

Know how to create a

chart from Excel

Know how to read the

chart (find a value given

a certain condition)

Know the characteristics,

and be able to pick the

best chart to convey info.

Documents

BUS304 – Data Presentation1 Graphs Visual presentation of data Pie Chart Bar Chart Line Chart Scatter Chart