Charts
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Charts are used to help people understand
numerical data through visualization.
Appropriate charts can provide different
perspectives, details, overviews,
generalizations, and trends in data.
 These visual language devices filter
knowledge and provide appropriate
chunking, structuring, and pacing in the
presentation of data.
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Scientists often distinguish charts from
graphs.
 Charts present numerical relations on a
comparative basis.
 Graphs present a functional relation
between dependent and independent
variables.
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Examples of scientific charts
Bar chart,
 pie chart,
 various pictorial charts
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Examples of scientific graphs
Continuous line plots on linear-linear
coordinate scales,
 on semi-logarithmic coordinate scales,
 on log-log coordinate scales
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Electronic spreadsheets usually do not make
that distinction.
 They take a more business orientation and
refer to them both as charts. That’s what we
do here, matching Excel’s terminology.
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Basic issues in designing and
implementing graphic
presentations:
Simplicity, clarity, and consistency are
essential for good chart design.
 Keep extraneous text to a minimum.
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Both legibility and readability can
be significantly improved through
the selection of graphic elements
and the layout of the material.
Legibility
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Legibility deals with the reader’s ability to
successfully find, identify, and absorb what
a chart denotes.
Readability
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Readability concerns the chart’s
interpretation and appeal.
Spreadsheet packages offer a
variety of chart types for
accomplishing this.
Excel supplies:
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Column
Bar
Line
Pie
XY (scatter)
Area
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Doughnut
Radar
Surface
Bubble
Stock
Cone, cylinder, and
pyramid
You can create any one of these in Excel by
first selecting the cells whose values are to
be displayed in the chart.
 Then click the Chart Wizard button on the
standard toolbar and choose from among
the options presented on the resulting series
of dialog boxes.
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Column charts
A column chart shows the data as vertical
bars.
 A column chart shows data changes over a
period of time or illustrates comparisons
among items.
 Categories are organized horizontally,
values vertically, to emphasize variation
over time.
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Stacked column charts show the
relationship of individual items to the
whole.
 Step charts are column charts without space
between the columns.
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The 3-D perspective column chart compares
data points along two axes.
 In this 3-D chart, you can compare four
quarters of sales performance in one
division with the performance of two other
divisions.
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90
80
70
60
50
East
West
North
40
30
20
10
0
1st Qtr
2nd Qtr
3rd Qtr
4th Qtr
Bar chart
A bar chart displays the data as horizontal
bars.
 It is used to illustrate comparisons among
individual items.
 Categories are organized vertically, values
horizontally, to focus on comparing values
and to place less emphasis on time.
 Stacked bar charts show the relationship of
individual items to the whole.
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Line chart
A line chart shows data plotted with or
without markers at the data point locations
and with or without line segments
connecting the points.
 A line chart shows trends in data at equal
intervals, discretely or continuously.
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Pie chart
A pie chart displays the data in a circle
divided into sectors.
 It shows the proportional size of items(out
of 100%) that make up a data series to the
sum of the items.
 NB: It always shows only one data series
and is useful when you want to emphasize a
significant element.
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To make small sectors/slices easier to see,
you can group them together as one item in
a pie chart and then break down that item in
a smaller pie or bar chart next to the main
chart.
XY (scatter) chart
A scatter chart is like a line chart but with a
greater variety of built-in axes for
proportional calibrations.
 An xy (scatter) chart either shows the
relationships among the numeric values in
several data series or plots two groups of
numbers as one series of xy coordinates.
 It shows uneven intervals or clusters of data
and is commonly used for scientific data.
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When you arrange your data, place x values
in one row or column, and then enter
corresponding y values in the adjacent rows
or columns.
Area chart
An area chart shows the area under a curve.
 It is usually used to emphasize the
magnitude of change over time.
 By displaying the sum of the plotted values,
an area chart also shows the relationship of
parts to a whole.
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For example, an area chart might emphasize
increased sales in Washington and illustrate the
contribution of each state to total sales.
Doughnut chart
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Like a pie chart, a doughnut chart shows the
relationship of parts to a whole, but it can
contain more than one data series. Each ring
of the doughnut chart represents a data
series.
Radar chart
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In a radar chart, each category has its own
value axis radiating from the center point.
Lines connect all the values in the same
series.
Surface chart
A surface chart is useful when you want to
find optimum combinations between two
sets of data.
 As in a topographic map, colors and
patterns indicate areas that are in the same
range of values.
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Bubble chart
A bubble chart is a type of xy (scatter)
chart. The size of the data marker indicates
the value of a third variable.
 To arrange your data, place the x values in
one row or column, and enter corresponding
y values and bubble sizes in the adjacent
rows or columns.
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For example, a chart might show that Company
A has the most products and the greatest market
share, but not the highest sales.
Stock chart
The high-low-close chart is often used to
illustrate stock prices.
 This chart can also be used for scientific
data, for example, to indicate temperature
changes.
 You must organize your data in the correct
order to create this and other stock charts.
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A stock chart that measures volume has two
value axes: one for the columns that
measure volume, the other for the stock
prices.
 You can include volume in a high-low-close
or open-high-low-close chart.
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Cone, cylinder, and pyramid
The cone, cylinder, and pyramid data
markers are variations of columns and bars.
They can add a special effect to 3-D column
and bar charts.
 So instead of having bars and columns you
use cones, cylinders, and pyramids.
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Some general guidelines in
designing any chart
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The ones most used in the business
environment are:
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Line
Bar and column
Pie
Line charts
These use a line to connect data points on a
measurable area, e.g. a Cartesian grid, to
show one dependent variable plotted against
an independent variable, such as time.
 With a line chart you can show long series
of data, interpolate between points,
extrapolate beyond known data values, and
compare several data lines.
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Line charts (cont.)
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The purpose of a line chart is to emphasize
a trend rather than actual amounts.
Guidelines in designing a line
chart
Since there are the data point lines and grid
and axis lines, make the data lines the
thickest.
 Make the grid lines thin or leave them out.
 Axes should be medium weight ; they
should be part of the rectangle that defines
the entire data area.
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Line chart (cont.)
If there’s enough room around the data area,
place the tick marks and scale values
outside the area.
 If there is more than one line, distinguish
them by color or texture.
 Avoid presenting more than 5 data lines.
 Be careful that when lines overlap, they are
in an order where textures or colors won’t
be mixed.
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Line chart (cont.)
For legibility keep all typography
horizontal, if possible.
 Sans serif fonts in a single font design are
often the most legible (Marcus 1992:101).
 The title can be centered but a stronger
structure is flush left aligned with the left
side of the data area rectangle.
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Line charts (cont.)
Keep the number of digits in the scales on
the axes at a minimum.
 Avoid labeling boxes or leader lines since
the chart might get too cluttered.
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Bar (horizontal) and column
(vertical) charts
Bar charts can be interchanged with line
charts in terms of purpose.
 But they are better for emphasizing actual
values or differences, especially between
positive and negative values.
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Bar and column charts (cont.)
Bar charts use thick lines, bars, or columns
to emphasize the magnitude or size of the
data value.
 They can stand separately, be grouped, or
stood end to end.
 Most of the issues relating to line charts
also apply to bar charts.
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Bar and column charts (cont.)
If you need to put data values near the end
of the bars or columns, make them small.
 The space between bars should be half the
width of the bars or less.(Or leave it out
altogether.)
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Bar and column charts (cont.)
Select colors and textures that do not cause
optical illusions or emphasize one segment
in comparison to others.
 Avoid putting more than three bars in a
group since the values they represent may
become confusing.
 One way to do this in Excel is to limit the
variables you will be charting to three or so.
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Pie charts
A pie chart shows the interrelation of
components to a whole.
 Its use is discouraged when you want a
reader to compare areas accurately either
within a chart or across several charts.
 It usually charts the values of a single
variable.
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Pie charts (cont.)
Place the title centered over or under the pie
if there aren’t any other constraints.
 But flush left or further left is OK if the title
were to obstruct a label.
 Place sector labels outside the sector.
 Arrange groups of labels simply.
 Use leader lines to identify small sectors but
don’t use many different angles.
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Pie charts (cont.)
Avoid using more than 7 sectors.
 Avoid having sectors that take up less 5% of
the pie/circle.
 Use textures and colors uniformly.
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Where does Excel get the
information it needs to create a
chart?
Labels of axes and legends come from
column and row headings
 Data points come from worksheet cell
values
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Some pointers for creating bar
and column charts
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1 To get the proper labels on legends and on
axes, you have to tell the system by
including in your selected region not only
the data points you want plotted but also the
labels from the label column and the label
row.
Qtr 1
Qtr 2
Qtr 3
Income
Local funds
State funds
National funds
Gifts
$250,000 $260,000 $270,400
$130,000 $135,200 $140,608
$50,000 $52,000 $54,080
$15,000 $15,600 $16,224
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2 For a bar or column chart, make sure your
selection delimits/describes a rectangle:
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3 Make sure the upper left-most cell is
blank. If it isn’t, Excel may have trouble
interpreting what you want as labels on your
legend, etc.
Upper left-most cell is
empty
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4. Select your labels and data points
systematically: e.g. top-to-bottom and leftto-right.
Top-to-bottom and
left-to-right
Types of things you can format
on a chart
Number formats, axis scale, and
tick marks:
You can specify the range of values
displayed on the value axis and change the
interval between values along the axis.
 For example, instead of starting at 0 (zero),
the chart in our example displays the range
of values $25 to $275.
 You can also specify whether an axis has
tick marks.
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You can format numbers in a chart as you
would numbers on a worksheet.
 To apply the most common number formats,
click the axis or data label that has the
number you want to format, and then apply
currency, percent, or comma style
formatting by clicking the buttons on the
Formatting toolbar.
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Formatting with colors, textures,
and gradient fills
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You can apply colors, borders, and fill effects to
data markers, the chart area, the plot area, and
other chart items.
To apply a fill effect, such as a texture or a picture,
click a chart item, click the arrow next to Fill
Color, and then click Fill Effects.
Next, select the options you want on the Gradient,
Texture, Pattern, and Picture tabs.
To format texts, including
rotating text
You can format text in a chart as you would
any other text:
 Click the text or item, and then change the
font, size, and color by clicking the buttons
on the Formatting toolbar.
 To rotate text 45 degrees up or down, click
the Angle Text Upward or Angle Text
Downward icons on the Chart toolbar.
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Special formatting options for
each chart type
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Special lines, bars, data markers, and other options
are available for different chart types.
For example, you can get a layered effect for
column and bar charts by changing the overlap
property for data series.
A line chart can have a shadow behind each
diamond-shaped marker and use a smoothed line.
Lines can connect the data series in a
stacked bar chart.
 To set special formatting for a data series,
click the data series, click Data Series on
the Format menu, and then select the
options you want on the Patterns and
Options tabs.
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You can choose to display or hide titles,
gridlines, axes, data labels, legends, or a
data table in your chart.
 Some of these items are available only in
certain types of charts.
 You can also display or hide some of these
items by using the buttons on the Chart
toolbar.
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To add labels to data points or
series:
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The chart type associated with the selected data
series or data point determines the type of label
you can add.
1 To add data labels to a data series, click the
data series.
To add a data label to a single data point, click the
data series that contains the data marker you want
to label, and then click the data marker for the data
point you want to label.
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2 On the Format menu, click Data Series or
Data Point.
3 On the Data Labels tab, select the options you
want.
Note: You can quickly label all data points. Click
the chart, click Chart Options on the Chart menu,
and then select the options you want on the Data
Labels tab.
To add a title to a chart
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1 Click the chart to which you want to add a
title.
2 On the Chart menu, click Chart Options, and
then click the Titles tab.
3 To add a chart title, click in the Chart title box,
and then type the text you want.
To add one or more axis titles, click in the
appropriate box for each title, and then type the
text you want.
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Note: To insert a line break in a chart title or
axis title, click the text on the chart, click
where you want to insert the line break, and
then press ENTER.
Change the size, color, or shape
of line, xy (scatter), or radar chart
markers
1 Click the line with the data markers you
want to change.
 2 On the Format menu, click Data Series,
and then click the Patterns tab.
 3 Under Marker, select the options you
want.
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To overlap or space data markers
in bar and column charts
You need to select only a single data series
to change the overlap or spacing of all data
series of the same chart type.
 1 Click a data series in the chart you want
to change.
 2 On the Format menu, click Data Series,
and then click the Options tab.
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3 To change the overlap of the data markers in
each category, enter a value between -100 and 100
in the Overlap box. The higher the value, the
greater the overlap within the category.
4 To change the spacing between categories of
data markers, enter a value between 0 (zero) and
500 in the Gap width box. The higher the value,
the greater the distance between each category.
To vary colors in the same data
series
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In a single-series chart, you can vary the colors of
data markers within the same data series. The
colors of slices in pie charts, which contain only
one series, are varied by default.
1 Click the data series you want to change the
colors for.
2 On the Format menu, click Data Series or
Data Point, and then click the Options tab.
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3 Select the Vary colors by point check
box or the Vary colors by slice check box.