Reinventing the Pie Chart:
Improved and Reliable Communication for This Popular Business Chart
LeHoy Bessler, Miller Brewing Company
Abstract and Introduction
Area Fill for Pie Slices
The SAS/GRAPH' implementation of the Pie Chart
can result in disappearing text for SLICE (name),
VALUE, and PERCENT (of whole) when a slice
becomes too small or when too many small slices
are adjacent.
For a simple pie chart, especially if without a legend,
the best area fill is EMPTY. However, for a
presentation, solid color may be more picturesque.
In any case, never use parallel lines or
cross-hatching. Gray shades or solid colors are the
best area fill.
Combining small slices into a non-informative
'OTHER" slice may be unacceptable. The desired
order of slices may be an essential requirement, or
rearranging slices may not help.
Order of Pie Slices
The SAS/GRAPH default order of pie slices· is by
slice name.
If SAS Institute enhances PROC GCHART with a pie
legend option, that will not suffice unless all three
items--SLlCE, VALUE, and PERCENT--can appear
in the legend.
But it is better to use the (by) DESCENDING (size)
option, to order the attention of the viewer.
"De-alphabetizing" the DESCENDING Feature
After struggling with this situation for years, and
developing an Enhanced Horizontal Bar Chart to
reliably provide all the features (except geometric) of
the Pie Chart, a simple solution--which requires an
unexpectedly relevant feature of Version 6--finally
occurred to me. The solution also eliminates the
16-character limit on SLICE names, a long-regretted
obstacle to elegant and clear communication.
To specify the area fill for pie slices, you need to
provide pattern statements, which are identified as
PATTERN1,PATTERN2, etc.
Even if you specify DESCENDING order for pie
slices, the PATTERNn area fills are always applied
by SAS/GRAPH to slices in alphabetic order of slice
name. The physical, DESCENDING-size order of the
slices is disregarded.
A method for pie legend generation is shown here,
but not "macro-ized". It uses hard-coding, rather
than having PERCENT, VALUE, and SLICE built and
passed as global variables, and having the legend
headings supplied as macro parameters. I leave
macro-ization as an exercise for the reader.
A pie chart looks best if you order gray-shaded slices
from lightest to darkest, particularly for the
DESCENDING option.
This paper covers above-described and other
"Problems and Perils of the Pie Chart", and how to
overcome them.
To aChieve this, you must first determine the "size
order for slice names", and then specify PATTERNn
gray shades accordingly. (See Appendix B and
Figure 4.)
When No Pie Chart Will Work
Pie Labels
The Enhanced Horizontal Bar Chart (Figure 2) is
needed if there are too many categories for a pie. It
provides image and detail optimally combined:
category name; percent of whole; graphic depiction
of relative size; and value (ranked). But it can't
present share-of-whole in the intrinsic geometric
manner of the pie chart. For the code to do this bar
chart, see my paper "Show Them What's Important:
Design and Construct Tables, Lists, Reports, and
Other Displays for Effective Communication",
elsewhere in these Proceedings.
I recommend NOHEADING.
Do not match the color of a label to that of slice--e.g.,
yellow text on white paper is impossible to read.
Black is usually the best color for text.
SAS/GRAPH appends .0 to integer VALUEs.
Suppress this with a FORMAT statement.
For the New, Improved Pie Chart, text and numbers
are in the legend; you specify SLICE-NONE,
PERCENT=NONE, and VALUE~NONE.
Pie Chart PERCENT Feature Perversity
The essential trick to the "Basic" Enhanced
Horizontal Bar Chart (not Figure 2). is to concatenate
percent-of-whole into the 16-character bar name
variable. But, for Figure 2, the longer bar name is
annotated. Also, NOSTATS is specified, and the bar
values are annotated at the bar ends, instead of
taking the default column at the margin.
PERCENT is only displayed at tenths or hundredths.
If the input VALUE is in tenths, the PERCENT will be
in tenths. If the input VALUE is in hundredths,
thousandths, or "finer", the PERCENT will be in
hundredths.
1022
You can get the PERCENT to be in tenths for any
VALUE finer than tenths. Reformat the input to give
to GCHART by first rounding with the statement
"TOGCHART - ROUND(VALUE,0.1);".
SUJ)press SLICE, VALUE, and PERCENT.
SAS/GRAPH may drop some ofthem anyhow.
Use a Ieft-justified footnote for each Slice. Indent
(uniformly) with leading blanks, if deSired.
Use the MARKER font for a first character of 'U" in
each footnote to produce the sample area-fill.
Use a uniform-width font (e.g., CENTXU) for Percent
of Whole, so that the digits, decimal points, and
percent signs are aligned.
However, if the input VALUE is integer, or integer
with zero(s) to right of decimal point, SAS/GRAPH
insists on displaying PERCENT to hundredths, no
matter how you try to trick it
For the New, Improved Pie Chart, the percent is in
the legend; you specify PERCENT-NONE, The
above remarks about PERCENT are irrelevant.
Also use a uniform-width font for Value.
If the slice name is at the end of the footnote, you
may use a variable-width font (e.g., CENTX) without
disturbing the alignment of the Percents or Values.
Worst Peril of SAs/GRAPH Pie Charts (Figure 3)
There is a limit of 8 pie slices ~.e., FOOTNOTE
statements), or 1 pie slices if headings for the
legend are not needed.
°
The SAS/GRAPH implementation of the Pie Chart
can result in disappearing text for SLICE (name),
VALUE, and PERCENT (of whole) when a slice
becomes too small orwhen too many small slices
are adjacent
For more slices, you have two choices. Use the
Enhanced Horizontal Bar Chart. Or output the
"naked" pie chart and a legend list made up of the
needed number of NOTE statements into two
separate GCAT entries, and then GREPLAY them
throug h a composite template.
The SAS/GRAPH code for the defective Pie Chart is
shown in Appendix A
As noted in the Abstract and Introduction, attempts
at circumvention may be ineffeCtive.
Just Say "No" to the 3D Designer Drug
New, Improved Pie Chart (Figure 4)
3D for a pie chart is a frill that distorts the message.
Please study the pie charts (not created with
SAS/GRAPH) in Figure 1 to see my point
As of Release 6.09, SAS/GRAPH does not support
a Pie legend. If SAS/GRAPH someday does, it may
not include all the features my New, Improved Pie
Chart can provide.
Notices
SAS/GRAPH is a registered trademark or trademark
of SAS Institute Inc. in the USA and other countries .
• denotes USA registration.
Fortunately, Version 6 provides the MARKER
(MARKERE) font. Using it, the "letter" U prints as
solid (empty) square. This enables you to produce a
block of sample area fill for a legend entry.
Author
Dr. LeRoy Bessler
P.O. Box 96
Fox POint, WI 53201-0096, USA
Telephone : 414-351-6748
The SAS/GRAPH code for the New, Improved Pie
Chart is shown in Appendix B.
5%---~
11%
11%
19%
~~201
~
5%
..-1-.--.
r---20%
5%
191
---~--401
Figure 1. 3D Pie Chart Distorts Relative Sizes of Slices (Compare 2D)
1023
Appendix A: Code for Defective Pie Chart:--Uses only SAS/GRAPH defaults, except OTHER=O
/~ statements for DATA Step, GOPTIONS, TITLEs, & FOOTNOTE ~/
PROC GCHART;
PIE BEVERAGE / OTHER=O SUHVAR=GALLONS TVPE=SUH PERCENT=OUTSIDE;
RUN;
Appendix B: Code for New, Improved Pie Chart
DATA;
INFILE CARDS;
INPUT aOl BEVERAGE $23.
CARDS;
Soft Drinks
Beer
Fruit Juices and Drinks
Bottled Water
Wine
Spirits
a25 GALLONS 4.1;
48.4
23.2
11.6
8.0
1.9
1.4
51. 270
24.570
12.370
8.570
2. OX
1. 570
RUN;
/~ GOPTIONS statement here ~/
TITLEl F=CENTX H=1.5 J=C
'1991 Relative Consumption of Beverages in Six Categories';
TITLE2 H=l.OO ' ';
TITLE3 F=CENTX H=1.50 J=C
'Estimates from "Beverage World 1992-1993 Data Bank"';
TITLE4 H=0.25 IN ' ';
FOOTNOTEl J=L H=1.50
F=CENTXU '
F=CENTXU
' , C=BLACK F=CENTXU 'Share
F=CENTX 'Gallons'
F=CENTXU'
,
F=CENTX 'Beverage Category';
,
.
,
,
FOOTNOTE2 J=L H=0.50
FOOTNOTE3 J=L H=1.50
F=CENTXU ,,
F=MARKERE C=BLACK 'U' C=BLACK F=CENTXU
51. 270 - 48.4 F=CENTX ,'Soft, Drinks';
FOOTNOTE4 J=L H=1.50
F=CENTXU
F=HARKER C=GRAVI 'U' C=BLACK F=CENTXU , 24.570 - 23.2 F=CENTX 'Beer'
, j
FOOTNOTES J=L H=1.50
F=CENTXU ,,
F=HARKER C=GRAV2 'U' C=BLACK F=CENTXU
12.370 - 11.6 F=CENTX ,'Fruit
, Juices and Drinks';
FOOTNOTE6 J=L H=1.50
F=CENTXU ,
F=HARKER C=GRAV3 'U' C=BLACK F=CENTXU
8.570 - 8.0 - ,
F=CENTX 'Bottled
Water';
,
FOOTNOTE7 J=L H=1.50
F=CENTXU ,,
F=HARKER C=GRAV4 'U' C=BLACK F=CENTXU
2.070 - 1.9 F=CENTX 'Wine'j
,
,
FOOTNOTE8 J=L H=1.50
F=CENTXU
F=HARKER C=BLACK 'U' C=BLACK F=CENTXU , 1.570 - 1.4 F=CENTX 'Spirits' j
FOOTNOTE9 H=0.50 IN ' ';
FOOTNOTEI0 J=L H=l.l F=TRIPLEX
,
Figure 4. New, Improved Pie Chart';
PATTERN 1 C=GRAVI V=PSOLID; /~ Beer
~/
PATTERN2 C=GRAV3 V=PSOLID; /~ Bottled Water
~/
PATTERN3 C=GRAV2 V=PSOLID; /~ Fruit Drinks/Juices ~/
PATTERN4 C=WHITE V=PSOLID; /~ Soft Drinks
~/
PATTERNS C=BLACK V=PSOLID; /~ Spirits
~/
PATTERN6 C=GRAV4 V=PSOLID; /~ Wine
~/
PROC GCHART;
PIE BEVERAGE / OTHER=O SUHVAR=GALLONS TVPE=SUH PERCENT=NONE
CLOCKWISE
COUTLINE = BLACK
DESCENDING
NOHEADING
SLICE
NONE
VALUE
NONE;
RUN;
1024
State and Local Government Employment By State In October 1991
State Name, Percent of USA Total, and Employee Count
10.9%
1,429,149
California
8.6%
1,123,044
New York
7.2%
951,388
Texas
5.0%
657,460
Florida
4.3%
565,158
Illinois
4.0%
530,147
Ohio
Pennsylvania
3.7%
485,736
Michigan
3.7%
480,402
3.2%
417,913
New Jersey
2.9%
383,290
Georgia
360,844
North Carolina 2.7%
2.6%
338,478
VirCiJinia
2.2%
288,789
Indl.ana
Massachusetts
2.1%
278,831
2.0%
266,290
washington
1.9%
256,022
Wisconsin
Tennessee
1.9%
249,897
1.9%
246,434
Missouri
Maryland
1.9%
245,953
1.9%
244,064
Lousiana
Minnesota
1.8%
235,058
1.8%
232,437
Alabama
South Carolina 1.5%
200,233
1.5%
195,563
Kentucky
Arizona
1.4%
189,447
1.4%
185,912
Colorado
Oklahoma
1.4%
185,106
1.2% ummm 164,052
Iowa
Oregon
1.2% mmmm 157,642
Connecticut
1.2% mmmm 155,718
Kansas
1.2% mmmm 154,745
1.2% mmmm 151,964
Mississippi
Arkansas
0.9% mmm 123,132
New Mexico
0.8% IIIiIIIl!II 100,602
Nebraska
0.7% I!iIiIII 98,219
west Virginia
0.7% IIIIIIIII!I 91,332
Utah
0.7% IIIIIIIII!I 90,727
Maine
0.5% IIIIii1 64,582
Hawaii
0.5% IIIIlIII 64,390
Nevada
0.5% I11III 62,680
0.4% IIIIiII 57,164
Idaho
Montana
0.4% II1II 52,006
New Hampshire
0.4% II1II 51,046
0.4% IIIiII 46,670
Rhode Island
0.3% l1li 43,978
Alaska
South Dakota
0.3% Ii!iI 38,054
Delaware
0.3% II1II 36,997
Wyoming
0.3% l1li 35,780
North Dakota
0.3% III 35,581
Vermont
0.2% m 30,236
USA Total
Figure 2. Annotated Ranked Horizontal Bar Chart:
For When No Pie Chart Will Work
1025
=
13,130,342
1991 Per Capita Consumption of Beverages in Six Categories·
Estimates from "Beverage World 1992 -1993 Data B3lJkI'
SUM of GALLONS by BEVERAGE
Bottled Water
8.0
8.47%
Beer
23.2
24.55%
Fruit Juices and
11.6
12.28%
Spirits
1.4
1. 481
Soft Drinks
48.4
51.221
Figure 3. Defective Pie Chart:
"Wine" label, value, percent Inissing, "Fruit Juices and Drinks" label truncated
1026
1991 Per Capita Consumption of Beverages in Six Categories
Estimates from IIBeverage World 1992 -1993 Data BanlCl
Share
Gallons
Beverage Category
51.2%
24.5%
tI~ 12.3%
~
8.5%
II
2.0%
1.5%
48.4
23.2
11 . 6
8.0
1.9
1.4
Soft Drinks
Beer
Fruit Juices and Drinks
Bottled Water
0
•
•
Wme
Spirits
Figure 4. New, Improved Pie Chart
1027