Microsoft Office Tutorials and References

In Depth Information

Chart Wizard; for Excel 2007 select the series, right click and select Format Data

series where a Secondary Axis is available. Additionally, if we display series on

separate graphs, we can impose similar scales on the multiple graphs to facilitate

equitable comparison. Being alert to these differences can change our assessment

of results.

4.
Fit the Chart Type by considering the graph’s purpose
—The choice of the chart

type should invariably be guided by one principle—
keep it simple
. There are

often many ways to display data, whether the data are cross-sectional or time

series. Consider the following ideas and questions relating to chart type selection.

Time Series Data (data related to a time axis)

a. Will the data be displayed over a chronological time horizon? If so, it is

considered time series data.

b. In business or economics, time series data are invariably displayed with time on

the horizontal axis.

c. With time series we can either display data discretely (bars) or continuously

(lines and area). If the ﬂow or continuity of data is important then Line and Area

graphs are preferred. Be careful that viewers not assume that they can locate

values between time increments, if these intermediate values are not meaningful.

Cross-sectional Data Time Snap-shot or (time dimension is not of primary

importance)

a. For data that is a single snap-shot of time or time is not our focus, column or bar

graphs are used most frequently. If you use column or bar graphs, it is important

to have category titles on axes (horizontal or vertical). If you do not use a column

or bar graph, then a Pie, Doughnut, Cone, or Pyramid graph may be appropriate.

Line graphs are usually not advisable for cross-sectional data.

b. Flat Pie graphs are far easier to read and interpret than 3-D Pie graphs. Also,

when data result in several very small pie segments, relative to others, then

precise comparisons can be difﬁcult.

c. Is the categorical order of the data important? There may be a natural order in

categories that should be preserved in the data presentation—e.g. the application

of chronologically successive marketing promotions in a sales campaign.

d. Displaying multiple series in a Doughnut graph can be confusing. The creation

of Doughnuts within Doughnuts can lead to implied proportional relationships

which do not exit.

Co-related Data

a. Scatter diagrams are excellent tools for viewing the co-relationship (correlation

statistical jargon) of one variable to another. They represent two associated data

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