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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"  
  "http://www.w3.org/TR/html4/loose.dtd">  
<html > 
<head><title>4 Guidelines on Graphics</title> 
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   <h3 class="sectionHead"><span class="titlemark">4   </span> <a 
 id="x5-460004"></a>Guidelines on Graphics</h3>
<!--l. 12--><p class="noindent">The present section is not about <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;or Ti<span 
class="cmti-10">k</span>Z, but about general guidelines and principles concerning the creation
of graphics for scientific presentations, papers, and books.
<!--l. 16--><p class="indent">   The guidelines in this section come from different sources. Many of them are just what I would like to claim is
&#8220;common sense,&#8221; some reflect my personal experience (though, hopefully, not my personal preferences), some come
from books (the bibliography is still missing, sorry) on graphic design and typography. The most influential
source are the brilliant books by Edward Tufte. While I do not agree with everything written in these
books, many of Tufte&#8217;s arguments are so convincing that I decided to repeat them in the following
guidelines.
<!--l. 29--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">4.1   </span> <a 
 id="x5-470004.1"></a>Should You Follow Guidelines?</h4>
<!--l. 31--><p class="noindent">The first thing you should ask yourself when someone presents a bunch of guidelines is: Should I really follow
these guidelines? This is an important questions, because there are good reasons not to follow general
guidelines.
     <ul class="itemize1">
     <li class="itemize">The person who setup the guidelines may have had other objectives than you do. For example, a
     guideline might say &#8220;use the color red for emphasis.&#8221; While this guideline makes perfect sense for, say,
     a presentation using a projector, red &#8220;color&#8221; has the <span 
class="cmti-10">opposite </span>effect of &#8220;emphasis&#8221; when printed using
     a black-and-white printer.
     <!--l. 44--><p class="noindent">Guidelines were almost always setup to address a specific situation. If you are not in this situation,
     following a guideline can do more harm than good.
     </li>
     <li class="itemize">The basic rule of typography is: &#8220;Every rule can be broken, as long as you are <span 
class="cmti-10">aware </span>that you are
     breaking a rule.&#8221; This rule also applies to graphics. Phrased differently, the basic rule states: &#8220;The only
     mistakes in typography are things done is ignorance.&#8221;
     <!--l. 54--><p class="noindent">When you are aware of a rule and when you decide that breaking the rule has a desirable effect, break
     the rule.
     </li>
     <li class="itemize">Some guidelines are simply <span 
class="cmti-10">wrong</span>, but everyone follows them out of tradition or is forced to do so.
     My favorite example is a guideline a software company I used to work for has set in a big project:
     All programmers had to declare the parameters of functions in <span 
class="cmti-10">increasing order of size</span>. So, one-byte
     parameters should come first, then two-byte parameters, and so on.
     <!--l. 64--><p class="noindent">This guideline is total nonsense. An (arguably) sensible guideline is &#8220;parameters must be declared
     alphabetically&#8221;  so  that  parameters  are  easier  to  find.  Another  (arguably)  sensible  guideline  is
     &#8220;parameters must be declared in decreasing order of size&#8221; so that less byte-alignment cache misses
     occur when the stack is accessed. The guideline the company used maximized cache misses and resulted
     in a more or less random ordering so that programmers constantly had to look up the parameter
     ordering.</li></ul>
<!--l. 74--><p class="indent">   So, before you apply a guideline or choose not to apply it, ask yourself these questions:
     <ol type="1" class="enumerate1" >
     <li class="enumerate" value="1" 
><a 
 id="x5-47002x1"></a>Does this guideline really address my situation?
     </li>
     <li class="enumerate" value="2" 
><a 
 id="x5-47004x2"></a>If you do the opposite a guideline says you should do, will the advantages outweigh the disadvantages
     this guideline was supposed to prevent?</li></ol>
                                                                                         
                                                                                         
<!--l. 87--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">4.2   </span> <a 
 id="x5-480004.2"></a>Planning the Time Needed for the Creation of Graphics</h4>
<!--l. 89--><p class="noindent">When you create a paper with numerous graphics, the time needed to create these graphics becomes an important
factor. How much time should you calculate for the creation of graphics?
<!--l. 93--><p class="indent">   As a general rule, assume that a graphic will need as much time to create as would a text of the same length. For
example, when I write a paper, I need about one hour per page for the first draft. Later, I need between two and
four hours per page for revisions. Thus, I expect to need about half an hour for the creation of <span 
class="cmti-10">a first</span>
<span 
class="cmti-10">draft </span>of a half page graphic. Later on, I expect another one to two hours before the final graphic is
finished.
<!--l. 101--><p class="indent">   In many publications, even in good journals, the authors and editors have obviously invested a lot of time on the
text, but seem to have spend about five minutes to create all of the graphics. Graphics often seem to have been
added as an &#8220;afterthought&#8221; or look like a screen shot of whatever the authors&#8217;s statistical software shows them. As
will be argued later on, the graphics that programs like <span 
class="cmcsc-10"><small 
class="small-caps">G</small><small 
class="small-caps">N</small><small 
class="small-caps">U</small><small 
class="small-caps">P</small><small 
class="small-caps">L</small><small 
class="small-caps">O</small><small 
class="small-caps">T</small> </span>produce by default are of poor
quality.
<!--l. 110--><p class="indent">   Creating informative graphics that help the reader and that fit together with the main text is a difficult, lengthy
process.
     <ul class="itemize1">
     <li class="itemize">Treat graphics as first-class citizens of your papers. They deserve as much time and energy as the text
     does.
     </li>
     <li class="itemize">Arguably, the creation of graphics deserves <span 
class="cmti-10">even more </span>time than the writing of the main text since
     more attention will be paid to the graphics and they will be looked at first.
     </li>
     <li class="itemize">Plan as much time for the creation and revision of a graphic as you would plan for text of the same
     size.
     </li>
     <li class="itemize">Difficult graphics with a high information density may require even more time.
     </li>
     <li class="itemize">Very simple graphics will require less time, but most likely you do not want to have &#8220;very simple
     graphics&#8221; in your paper, anyway; just as you would not like to have a &#8220;very simple text&#8221; of the same
     size.</li></ul>
<!--l. 135--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">4.3   </span> <a 
 id="x5-490004.3"></a>Workflow for Creating a Graphic</h4>
<!--l. 137--><p class="noindent">When you write a (scientific) paper, you will most likely follow the following pattern: You have some
results/ideas that you would like to report about. The creation of the paper will typically start with
compiling a rough outline. Then, the different sections are filled with text to create a first draft. This
draft is then revised repeatedly until, often after substantial revision, a final paper results. In a good
journal paper there is typically not be a single sentence that has survived unmodified from the first
draft.
<!--l. 146--><p class="indent">   Creating a graphics follows the same pattern:
     <ul class="itemize1">
     <li class="itemize">Decide on what the graphic should communicate. Make this a conscious decision, that is, determine
     &#8220;What is the graphic supposed to tell the reader?&#8221;
     </li>
     <li class="itemize">Create an &#8220;outline,&#8221; that is, the rough overall &#8220;shape&#8221; of the graphic, containing the most crucial
     elements. Often, it is useful to do this using pencil and paper.
     </li>
     <li class="itemize">Fill out the finer details of the graphic to create a first draft.
     </li>
     <li class="itemize">Revise the graphic repeatedly along with the rest of the paper.</li></ul>
                                                                                         
                                                                                         
<!--l. 166--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">4.4   </span> <a 
 id="x5-500004.4"></a>Linking Graphics With the Main Text</h4>
<!--l. 168--><p class="noindent">Graphics can be placed at different places in a text. Either, they can be inlined, meaning they are
somewhere &#8220;in the middle of the text&#8221; or they can be placed in standalone &#8220;figures.&#8221; Since printers
(the people) like to have their pages &#8220;filled,&#8221; (both for aesthetic and economic reasons) standalone
figures may traditionally be placed on pages in the document far removed from the main text that
refers to them. <span class="LATEX">L<span class="A">A</span><span class="TEX">T<span 
class="E">E</span>X</span></span>&nbsp;and <span class="TEX">T<span 
class="E">E</span>X</span>&nbsp;tend to encourage this &#8220;drifting away&#8221; of graphics for technical
reasons.
<!--l. 177--><p class="indent">   When a graphic is inlined, it will more or less automatically be linked with the main text in the sense that the
labels of the graphic will be implicitly explained by the surrounding text. Also, the main text will typically make it
clear what the graphic is about and what is shown.
<!--l. 183--><p class="indent">   Quite differently, a standalone figure will often be viewed at a time when the main text that this graphic belongs
to either has not yet been read or has been read some time ago. For this reason, you should follow the following
guidelines when creating standalone figures:
     <ul class="itemize1">
     <li class="itemize">Standalone figures should have a caption than should make them &#8220;understandable by themselves.&#8221;
     <!--l. 192--><p class="noindent">For example, suppose a graphic shows an example of the different stages of a quicksort algorithm. Then
     the figure&#8217;s caption should, at the very least, inform the reader that &#8220;The figure shows the different
     stages of the quicksort algorithm introduced on page xyz.&#8221; and not just &#8220;Quicksort algorithm.&#8221;
     </li>
     <li class="itemize">A good caption adds as much context information as possible. For example, you could say: &#8220;The figure
     shows the different stages of the quicksort algorithm introduced on page xyz. In the first line, the pivot
     element 5 is chosen. This causes...&#8221; While this information can also be given in the main text, putting
     it in the caption will ensure that the context is kept. Do not feel afraid of a 5-line caption. (Your editor
     may hate you for this. Consider hating them back.)
     </li>
     <li class="itemize">Reference the graphic in your main text as in &#8220;For an example of quicksort &#8216;in action,&#8217; see Figure&nbsp;2.1
     on page xyz.&#8221;
     </li>
     <li class="itemize">Most books on style and typography recommend that you do not use abbreviations as in &#8220;Fig.&nbsp;2.1&#8221;
     but write &#8220;Figure 2.1.&#8221;
     <!--l. 213--><p class="noindent">The  main  argument  against  abbreviations  is  that  &#8220;a  period  is  too  valuable  to  waste  it  on  an
     abbreviation.&#8221; The idea is that a period will make the reader assume that the sentence ends after &#8220;Fig&#8221;
     and it takes a &#8220;conscious backtracking&#8221; to realize that the sentence did not end after all.
     <!--l. 219--><p class="noindent">The argument in favor of abbreviations is that they save space.
     <!--l. 221--><p class="noindent">Personally, I am not really convinced by either argument. On the one hand, I have not yet seen any
     hard evidence that abbreviations slow readers down. On the other hand, abbreviating all &#8220;Figure&#8221; by
     &#8220;Fig.&#8221;&nbsp;is most unlikely to save even a single line in most documents.
     <!--l. 227--><p class="noindent">I avoid abbreviations.</li></ul>
<!--l. 232--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">4.5   </span> <a 
 id="x5-510004.5"></a>Consistency Between Graphics and Text</h4>
<!--l. 234--><p class="noindent">Perhaps the most common &#8220;mistake&#8221; people do when creating graphics (remember that a &#8220;mistake&#8221; in design is
always just &#8220;ignorance&#8221;) is to have a mismatch between the way their graphics look and the way their text
looks.
<!--l. 239--><p class="indent">   It is quite common that authors use several different programs for creating the graphics of a paper. An author
might produce some plots using <span 
class="cmcsc-10"><small 
class="small-caps">G</small><small 
class="small-caps">N</small><small 
class="small-caps">U</small><small 
class="small-caps">P</small><small 
class="small-caps">L</small><small 
class="small-caps">O</small><small 
class="small-caps">T</small></span>, a diagram using <span 
class="cmcsc-10"><small 
class="small-caps">X</small><small 
class="small-caps">F</small><small 
class="small-caps">I</small><small 
class="small-caps">G</small></span>, and include an <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">.eps</span></span></span> graphic a coauthor
contributed using some unknown program. All these graphics will, most likely, use different line widths, different
fonts, and have different sizes. In addition, authors often use options like <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">[height=5cm]</span></span></span> when including graphics to
scale them to some &#8220;nice size.&#8221;
                                                                                         
                                                                                         
<!--l. 248--><p class="indent">   If the same approach were taken to writing the main text, every section would be written in a different font at a
different size. In some sections all theorems would be underlined, in another they would be printed
all in uppercase letters, and in another in red. In addition, the margins would be different on each
page.
<!--l. 254--><p class="indent">   Readers and editors would not tolerate a text if it were written in this fashion, but with graphics they often have
to.
<!--l. 257--><p class="indent">   To create consistency between graphics and text, stick to the following guidelines:
     <ul class="itemize1">
     <li class="itemize">Do not scale graphics.
     <!--l. 263--><p class="noindent">This means that when generating graphics using an external program, create them &#8220;at the right size.&#8221;
     </li>
     <li class="itemize">Use the same font(s) both in graphics and the body text.
     </li>
     <li class="itemize">Use the same line width in text and graphics.
     <!--l. 270--><p class="noindent">The &#8220;line width&#8221; for normal text is the width of the stem of letters like T. For <span class="TEX">T<span 
class="E">E</span>X</span>, this is usually
     0<span 
class="cmmi-10">.</span>4pt. However, some journals will not accept graphics with a normal line width below 0<span 
class="cmmi-10">.</span>5pt.
     </li>
     <li class="itemize">When using colors, use a consistent color coding in the text and in graphics. For example, if red is
     supposed to alert the reader to something in the main text, use red also in graphics for important parts
     of the graphic. If blue is used for structural elements like headlines and section titles, use blue also for
     structural elements of your graphic.
     <!--l. 282--><p class="noindent">However, graphics may also use a logical intrinsic color coding. For example, no matter what colors
     you normally use, readers will generally assume, say, that the color green as &#8220;positive, go, ok&#8221; and red
     as &#8220;alert, warning, action.&#8221;</li></ul>
<!--l. 288--><p class="indent">   Creating consistency when using different graphic programs is almost impossible. For this reason, you should
consider sticking to a single graphic program.
<!--l. 293--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">4.6   </span> <a 
 id="x5-520004.6"></a>Labels in Graphics</h4>
<!--l. 295--><p class="noindent">Almost all graphics will contain labels, that is, pieces of text that explain parts of the graphics. When placing labels,
stick to the following guidelines:
     <ul class="itemize1">
     <li class="itemize">Follow the rule of consistency when placing labels. You should do so in two ways: First, be consistent
     with the main text, that is, use the same font as the main text also for labels. Second, be consistent
     between labels, that is, if you format some labels in some particular way, format all labels in this way.
     </li>
     <li class="itemize">In addition to using the same fonts in text and graphics, you should also use the same notation. For
     example, if you write 1<span 
class="cmmi-10">/</span>2 in your main text, also use &#8220;1<span 
class="cmmi-10">/</span>2&#8221; as labels in graphics, not &#8220;0.5&#8221;. A <span 
class="cmmi-10"><img 
src="cmmi10-19.png" alt="p" class="10x-x-19" /> </span>is a
     &#8220;<span 
class="cmmi-10"><img 
src="cmmi10-19.png" alt="p" class="10x-x-19" /></span>&#8221; and not &#8220;3<span 
class="cmmi-10">.</span>141&#8221;. Finally, e<sup ><span 
class="cmsy-7">-</span><span 
class="cmr-7">i</span><span 
class="cmmi-7"><img 
src="cmmi7-19.png" alt="p" class="7x-x-19" /></span></sup> is &#8220;e<sup ><span 
class="cmsy-7">-</span><span 
class="cmr-7">i</span><span 
class="cmmi-7"><img 
src="cmmi7-19.png" alt="p" class="7x-x-19" /></span></sup>&#8221;, not &#8220;<span 
class="cmsy-10">-</span>1&#8221;, let alone &#8220;-1&#8221;.
     </li>
     <li class="itemize">Labels should be legible. They should not only have a reasonably large size, they also should not be
     obscured by lines or other text. This also applies to of lines and text <span 
class="cmti-10">behind </span>the labels.
     </li>
     <li class="itemize">Labels should be &#8220;in place.&#8221; Whenever there is enough space, labels should be placed next to the
     thing they label. Only if necessary, add a (subdued) line from the label to the labeled object. Try to
     avoid labels that only reference explanations in external legends. Reader have to jump back and forth
     between the explanation and the object that is described.
     </li>
     <li class="itemize">Consider subduing &#8220;unimportant&#8221; labels using, for example, a gray color. This will keep the focus on
     the actual graphic.</li></ul>
                                                                                         
                                                                                         
<!--l. 332--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">4.7   </span> <a 
 id="x5-530004.7"></a>Plots and Charts</h4>
<!--l. 334--><p class="noindent">One of the most frequent kind of graphics, especially in scientific papers, are <span 
class="cmti-10">plots</span>. They come in a large
variety, including simple line plots, parametric plots, three dimensional plots, pie charts, and many
more.
<!--l. 339--><p class="indent">   Unfortunately, plots are notoriously hard to get right. Partly, the default settings of programs like
<span 
class="cmcsc-10"><small 
class="small-caps">G</small><small 
class="small-caps">N</small><small 
class="small-caps">U</small><small 
class="small-caps">P</small><small 
class="small-caps">L</small><small 
class="small-caps">O</small><small 
class="small-caps">T</small> </span>or Excel are to blame for this since these programs make it very convenient to create bad
plots.
<!--l. 344--><p class="indent">   The first question you should ask yourself when creating a plot is the following:
     <ul class="itemize1">
     <li class="itemize">Are there enough data points to merit a plot?</li></ul>
<!--l. 351--><p class="indent">   If the answer is &#8220;not really,&#8221; use a table.
<!--l. 353--><p class="indent">   A typical situation where a plot is unnecessary is when people present a few numbers in a bar diagram. Here is a
real-life example: At the end of a seminar a lecturer asked the participants for feedback. Of the 50 participants, 30
returned the feedback form. According to the feedback, three participants considered the seminar &#8220;very good,&#8221;
nine considered it &#8220;good,&#8221; ten &#8220;ok,&#8221; eight &#8220;bad,&#8221; and no one thought that the seminar was &#8220;very
bad.&#8221;
<!--l. 361--><p class="indent">   A simple way of summing up this information is the following table:
   <div class="tabular"><table class="tabular" 
cellspacing="0" cellpadding="0"  
frame="void" id="TBL-63-" ><colgroup id="TBL-63-1g"><col 
id="TBL-63-1"><col 
id="TBL-63-2"><col 
id="TBL-63-3"></colgroup><tr  
 valign="baseline" id="TBL-63-1-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-1-1"  
class="td11">  <span 
class="cmti-10">Rating given  </span></td><td  align="left" id="TBL-63-1-2"  
class="td11">  <!--l. 365--><p class="noindent"><span 
class="cmti-10">Participants</span>
  <span 
class="cmti-10">(out</span>
  <span 
class="cmti-10">of</span>
  <span 
class="cmti-10">50)</span>
  <span 
class="cmti-10">who</span>
  <span 
class="cmti-10">gave</span>
  <span 
class="cmti-10">this</span>
  <span 
class="cmti-10">rating</span>                        </td><td  align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-1-3"  
class="td11">  <span 
class="cmti-10">Percentage  </span></td>
</tr><tr 
class="vspace" style="font-size:17.50002pt"><td 
>&nbsp;</td><td 
>&nbsp;</td><td 
>&nbsp;</td></tr><tr  
 valign="baseline" id="TBL-63-2-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-2-1"  
class="td11">  &#8220;very good&#8221;  </td><td  align="left" id="TBL-63-2-2"  
class="td11">  <!--l. 367--><p class="noindent">                3                </td><td  align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-2-3"  
class="td11">            6%  </td>
</tr><tr  
 valign="baseline" id="TBL-63-3-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-3-1"  
class="td11">  &#8220;good&#8221;         </td><td  align="left" id="TBL-63-3-2"  
class="td11">  <!--l. 368--><p class="noindent">                9                </td><td  align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-3-3"  
class="td11">           18%  </td>
</tr><tr  
 valign="baseline" id="TBL-63-4-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-4-1"  
class="td11">  &#8220;ok&#8221;            </td><td  align="left" id="TBL-63-4-2"  
class="td11">  <!--l. 369--><p class="noindent">               10                </td><td  align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-4-3"  
class="td11">           20%  </td>
</tr><tr  
 valign="baseline" id="TBL-63-5-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-5-1"  
class="td11">  &#8220;bad&#8221;           </td><td  align="left" id="TBL-63-5-2"  
class="td11">  <!--l. 370--><p class="noindent">                8                </td><td  align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-5-3"  
class="td11">           16%  </td>
</tr><tr  
 valign="baseline" id="TBL-63-6-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-6-1"  
class="td11">  &#8220;very bad&#8221;    </td><td  align="left" id="TBL-63-6-2"  
class="td11">  <!--l. 371--><p class="noindent">                0                </td><td  align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-6-3"  
class="td11">            0%  </td>
</tr><tr 
class="vspace" style="font-size:5.69054pt"><td 
>&nbsp;</td><td 
>&nbsp;</td><td 
>&nbsp;</td></tr><tr  
 valign="baseline" id="TBL-63-7-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-7-1"  
class="td11">  none            </td><td  align="left" id="TBL-63-7-2"  
class="td11">  <!--l. 372--><p class="noindent">               20                </td><td  align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-7-3"  
class="td11">           40%  </td>
</tr><tr  
 valign="baseline" id="TBL-63-8-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-8-1"  
class="td11">                    </td> </tr></table>
</div>
<!--l. 376--><p class="indent">   What the lecturer did was to visualize the data using a 3D bar diagram. It looked like this:
<!--l. 400--><p class="indent">   <object data="pgfmanual-60.svg" width="269.42331 " height="193.05234 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>
<!--l. 403--><p class="indent">   Both the table and the &#8220;plot&#8221; have about the same size. If your first thought is &#8220;the graphic looks nicer
than the table,&#8221; try to answer the following questions based on the information in the table or in the
graphic:
                                                                                         
                                                                                         
     <ol type="1" class="enumerate1" >
     <li class="enumerate" value="1" 
><a 
 id="x5-53002x1"></a>How many participants where there?
     </li>
     <li class="enumerate" value="2" 
><a 
 id="x5-53004x2"></a>How many participants returned the feedback form?
     </li>
     <li class="enumerate" value="3" 
><a 
 id="x5-53006x3"></a>What percentage of the participants returned the feedback form?
     </li>
     <li class="enumerate" value="4" 
><a 
 id="x5-53008x4"></a>How many participants checked &#8220;very good&#8221;?
     </li>
     <li class="enumerate" value="5" 
><a 
 id="x5-53010x5"></a>What percentage out of all participants checked &#8220;very good&#8221;?
     </li>
     <li class="enumerate" value="6" 
><a 
 id="x5-53012x6"></a>Did more than a quarter of the participants check &#8220;bad&#8221; or &#8220;very bad&#8221;?
     </li>
     <li class="enumerate" value="7" 
><a 
 id="x5-53014x7"></a>What percentage of the participants that returned the form checked &#8220;very good&#8221;?</li></ol>
<!--l. 424--><p class="indent">   Sadly, the graphic does not allow us to answer <span 
class="cmti-10">a single one of these questions</span>. The table answers all of them
directly, except for the last one. In essence, the information density of the graphic is very nearly zero. The table has
a much higher information density; despite the fact that it uses quite a lot of white space to present a few
numbers.
<!--l. 430--><p class="indent">   Here is the list of things that went wrong with the 3D-bar diagram:
     <ul class="itemize1">
     <li class="itemize">The whole graphic is dominated by irritating background lines.
     </li>
     <li class="itemize">It is not clear what the numbers at the left mean; presumably percentages, but it might also be the
     absolute number of participants.
     </li>
     <li class="itemize">The labels at the bottom are rotated, making them hard to read.
     <!--l. 441--><p class="noindent">(In the real presentation that I saw, the text was rendered at a very low resolution with about 10 by
     6 pixels per letter with wrong kerning, making the rotated text almost impossible to read.)
     </li>
     <li class="itemize">The third dimension adds complexity to the graphic without adding information.
     </li>
     <li class="itemize">The three dimensional setup makes it much harder to gauge the height of the bars correctly. Consider
     the &#8220;bad&#8221; bar. It the number this bar stands for more than 20 or less? While the front of the bar is
     below the 20 line, the back of the bar (which counts) is above.
     </li>
     <li class="itemize">It is impossible to tell which numbers are represented by the bars. Thus, the bars needlessly hide the
     information these bars are all about.
     </li>
     <li class="itemize">What do the bar heights add up to? Is it 100% or 60%?
     </li>
     <li class="itemize">Does the bar for &#8220;very bad&#8221; represent 0 or&nbsp;1?
     </li>
     <li class="itemize">Why are the bars blue?</li></ul>
<!--l. 464--><p class="indent">   You might argue that in the example the exact numbers are not important for the graphic. The important things
is the &#8220;message,&#8221; which is that there are more &#8220;very good&#8221; and &#8220;good&#8221; ratings than &#8220;bad&#8221; and &#8220;very bad.&#8221;
However, to convey this message either use a sentence that says so or use a graphic that conveys this message more
clearly:
                                                                                         
                                                                                         
<!--l. 503--><p class="indent">   <object data="pgfmanual-61.svg" width="424.91754 " height="224.69525 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>
<!--l. 506--><p class="indent">   The above graphic has about the same information density as the table (about the same size and the same
numbers are shown). In addition, one can directly &#8220;see&#8221; that there are more good or very good ratings than bad
ones. One can also &#8220;see&#8221; that the number of people who gave no rating at all is not negligible, which is quite
common for feedback forms.
<!--l. 513--><p class="indent">   Charts are not always a good idea. Let us look at an example that I redrew from a pie chart in <span 
class="cmti-10">Die Zeit</span>, June
4th, 2005:
<!--l. 606--><p class="indent">   <object data="pgfmanual-62.svg" width="595.82195 " height="237.71802 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>
<!--l. 608--><p class="indent">   This graphic has been redrawn in Ti<span 
class="cmti-10">k</span>Z, but the original looks very similar.
<!--l. 611--><p class="indent">   At first sight, the graphic looks &#8220;nice and informative,&#8221; but there are a lot of things that went
wrong:
     <ul class="itemize1">
     <li class="itemize">The chart is three dimensional. However, the shadings add nothing &#8220;information-wise,&#8221; at best, they
     distract.
     </li>
     <li class="itemize">In a 3D-pie-chart the relative sizes are very strongly distorted. For example, the area taken up by the
     gray color of &#8220;Braunkohle&#8221; is larger than the area taken up by the green color of &#8220;Kernenergie&#8221; <span 
class="cmti-10">despite</span>
     <span 
class="cmti-10">the fact that the percentage of Braunkohle is less than the percentage of Kernenergie</span>.
     </li>
     <li class="itemize">The 3D-distortion gets worse for small areas. The area of &#8220;Regenerative&#8221; somewhat larger than the
     area of &#8220;Erdgas.&#8221; The area of &#8220;Wind&#8221; is slightly smaller than the area of &#8220;Mineral&ouml;lprodukte&#8221; <span 
class="cmti-10">although</span>
     <span 
class="cmti-10">the percentage of Wind is nearly three times larger than the percentage of Mineral</span><span 
class="cmti-10">&ouml;lprodukte.</span>
                                                                                         
                                                                                         
     <!--l. 632--><p class="noindent">In the last case, the different sizes are only partly due to distortion. The designer(s) of the original
     graphic have also made the &#8220;Wind&#8221; slice too small, even taking distortion into account. (Just compare
     the size of &#8220;Wind&#8221; to &#8220;Regenerative&#8221; in general.)
     </li>
     <li class="itemize">According to its caption, this chart is supposed to inform us that coal was the most important energy
     source in Germany in 2004. Ignoring the strong distortions caused by the superfluous and misleading
     3D-setup, it takes quite a while for this message to get across.
     <!--l. 644--><p class="noindent">Coal as an energy source is split up into two slices: one for &#8220;Steinkohle&#8221; and one for &#8220;Braunkohle&#8221; (two
     different kinds of coal). When you add them up, you see that the whole lower half of the pie chart is
     taken up by coal.
     <!--l. 649--><p class="noindent">The two areas for the different kinds of coal are not visually linked at all. Rather, two different colors
     are used, the labels are on different sides of the graphic. By comparison, &#8220;Regenerative&#8221; and &#8220;Wind&#8221;
     are very closely linked.
     </li>
     <li class="itemize">The  color  coding  of  the  graphic  follows  no  logical  pattern  at  all.  Why  is  nuclear  energy  green?
     Regenerative energy is light blue, &#8220;other sources&#8221; are blue. It seems more like a joke that the area for
     &#8220;Braunkohle&#8221; (which literally translates to &#8220;brown coal&#8221;) is stone gray, while the area for &#8220;Steinkohle&#8221;
     (which literally translates to &#8220;stone coal&#8221;) is brown.
     </li>
     <li class="itemize">The area with the lightest color is used for &#8220;Erdgas.&#8221; This area stands out most because of the brighter
     color. However, for this chart &#8220;Erdgas&#8221; is not really important at all.</li></ul>
<!--l. 665--><p class="noindent">Edward Tufte calls graphics like the above &#8220;chart junk.&#8221;
<!--l. 667--><p class="indent">   Here are a few recommendations that may help you avoid producing chart junk:
     <ul class="itemize1">
     <li class="itemize">Do not use 3D pie charts. They are <span 
class="cmti-10">evil</span>.
     </li>
     <li class="itemize">Consider using a table instead of a pie chart.
     </li>
     <li class="itemize">Due not apply colors randomly; use them to direct the readers&#8217;s focus and to group things.
     </li>
     <li class="itemize">Do not use background patterns, like a crosshatch or diagonal lines, instead of colors. They distract.
     Background patterns in information graphics are <span 
class="cmti-10">evil</span>.</li></ul>
<!--l. 684--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">4.8   </span> <a 
 id="x5-540004.8"></a>Attention and Distraction</h4>
<!--l. 686--><p class="noindent">Pick up your favorite fiction novel and have a look at a typical page. You will notice that the page is very uniform.
Nothing is there to distract the reader while reading; no large headlines, no bold text, no large white areas. Indeed,
even when the author does wish to emphasize something, this is done using italic letters. Such letters blend nicely
with the main text--at a distance you will not be able to tell whether a page contains italic letters, but you would
notice a single bold word immediately. The reason novels are typeset this way is the following paradigm: Avoid
distractions.
<!--l. 696--><p class="indent">   Good typography (like good organization) is something you do <span 
class="cmti-10">not </span>notice. The job of typography is to make
reading the text, that is, &#8220;absorbing&#8221; its information content, as effortless as possible. For a novel, readers absorb
the content by reading the text line-by-line, as if they were listening to someone telling the story. In this situation
anything on the page that distracts the eye from going quickly and evenly from line to line will make the text harder
to read.
<!--l. 705--><p class="indent">   Now, pick up your favorite weekly magazine or newspaper and have a look at a typical page. You will notice that
there is quite a lot &#8220;going on&#8221; on the page. Fonts are used at different sizes and in different arrangements, the text is
organized in narrow columns, typically interleaved with pictures. The reason magazines are typeset in this way is
another paradigm: Steer attention.
                                                                                         
                                                                                         
<!--l. 713--><p class="indent">   Readers will not read a magazine like a novel. Instead of reading a magazine line-by-line, we use headlines and
short abstracts to check whether we want to read a certain article or not. The job of typography is to steer our
attention to these abstracts and headlines, first. Once we have decided that we want to read an article, however, we
no longer tolerate distractions, which is why the main text of articles is typeset exactly the same way as a
novel.
<!--l. 721--><p class="indent">   The two principles &#8220;avoid distractions&#8221; and &#8220;steer attention&#8221; also apply to graphics. When you design a graphic,
you should eliminate everything that will &#8220;distract the eye.&#8221; At the same time, you should try to
actively help the reader &#8220;through the graphic&#8221; by using fonts/colors/line widths to highlight different
parts.
<!--l. 727--><p class="indent">   Here is a non-exhaustive list of things that can distract readers:
     <ul class="itemize1">
     <li class="itemize">Strong contrasts will always be registered first by the eye. For example, consider the following two
     grids:
     <!--l. 737--><p class="noindent"><object data="pgfmanual-63.svg" width="161.5327 " height="54.86644 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>
     <!--l. 740--><p class="noindent">Even though the left grid comes first in our normal reading order, the right one is much more likely to be seen
     first: The white-to-black contrast is higher than the gray-to-white contrast. In addition, there are more
     &#8220;places&#8221; adding to the overall contrast in the right grid.
     <!--l. 746--><p class="noindent">Things like grids and, more generally, help lines usually should not grab the attention of the readers and,
     hence, should be typeset with a low contrast to the background. Also, a loosely-spaced grid is less distracting
     than a very closely-spaced grid.
     </li>
     <li class="itemize">Dashed lines create many points at which there is black-to-white contrast. Dashed or dotted lines can be very
     distracting and, hence, should be avoided in general.
     <!--l. 755--><p class="noindent">Do not use different dashing patterns to differentiate curves in plots. You loose data points this way and the
     eye is not particularly good at &#8220;grouping things according to a dashing pattern.&#8221; The eye is <span 
class="cmti-10">much </span>better at
     grouping things according to colors.
     </li>
     <li class="itemize">Background patterns filling an area using diagonal lines or horizontal and vertical lines or just dots are almost
     always distracting and, usually, serve no real purpose.
     </li>
     <li class="itemize">Background images and shadings distract and only seldom add anything of importance to a
     graphic.
     </li>
     <li class="itemize">Cute little cliparts can easily draw attention away from the data.</li></ul>
                                                                                         
                                                                                         
                                                                                         
                                                                                         
                                                                                         
                                                                                         
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