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diff --git a/Master/texmf-dist/doc/generic/pgf/text-en/pgfmanual-en-guidelines.tex b/Master/texmf-dist/doc/generic/pgf/text-en/pgfmanual-en-guidelines.tex index 5a5a7b75957..a91cd43452b 100644 --- a/Master/texmf-dist/doc/generic/pgf/text-en/pgfmanual-en-guidelines.tex +++ b/Master/texmf-dist/doc/generic/pgf/text-en/pgfmanual-en-guidelines.tex @@ -10,304 +10,267 @@ \section{Guidelines on Graphics} -The present section is not about \pgfname\ or \tikzname, but about -general guidelines and principles concerning the creation of -graphics for scientific presentations, papers, and books. - -The guidelines in this section come from different sources. Many of -them are just what I would like to claim is ``common sense,'' 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's arguments are so convincing that I decided to -repeat them in the following guidelines. +The present section is not about \pgfname\ or \tikzname, but about general +guidelines and principles concerning the creation of graphics for scientific +presentations, papers, and books. + +The guidelines in this section come from different sources. Many of them are +just what I would like to claim is ``common sense'', 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's arguments are so convincing that I decided to repeat them in the +following guidelines. 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 question, because there are good reasons not to follow -general guidelines. The person who set up the guidelines may have had other -objectives than you do. For example, a guideline might say ``use the -color red for emphasis.'' While this guideline makes perfect sense -for, say, a presentation using a projector, red ``color'' has the -\emph{opposite} effect of ``emphasis'' when printed using a -black-and-white printer. Guidelines were almost always set up to -address a specific situation. If you are not in this situation, -following a guideline can do more harm than good. - -The second thing you should be aware of is the basic rule of -typography is: ``Every rule can be broken, as long as you are -\emph{aware} that you are breaking a rule.'' This rule also applies -to graphics. Phrased differently, the basic rule states: ``The only -mistakes in typography are things done in ignorance.'' When you are -aware of a rule and when you decide that breaking the rule has a -desirable effect, break the rule. +guidelines is: Should I really follow these guidelines? This is an important +question, because there are good reasons not to follow general guidelines. The +person who set up the guidelines may have had other objectives than you do. For +example, a guideline might say ``use the color red for emphasis''. While this +guideline makes perfect sense for, say, a presentation using a projector, red +``color'' has the \emph{opposite} effect of ``emphasis'' when printed using a +black-and-white printer. Guidelines were almost always set up to address a +specific situation. If you are not in this situation, following a guideline can +do more harm than good. + +The second thing you should be aware of is the basic rule of typography is: +``Every rule can be broken, as long as you are \emph{aware} that you are +breaking a rule.'' This rule also applies to graphics. Phrased differently, the +basic rule states: ``The only mistakes in typography are things done in +ignorance.'' When you are aware of a rule and when you decide that breaking the +rule has a desirable effect, break the rule. \subsection{Planning the Time Needed for the Creation of Graphics} -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? - -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 \emph{a first draft} of a half page graphic. Later on, I -expect another one to two hours before the final graphic is finished. - -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 -``afterthought'' or look like a screen shot of whatever the authors's -statistical software shows them. As will be argued later on, the -graphics that programs like \textsc{gnuplot} produce by default are of -poor quality. - -Creating informative graphics that help the reader and that fit -together with the main text is a difficult, lengthy process. +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? + +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 \emph{a first draft} of a half page graphic. Later on, I expect +another one to two hours before the final graphic is finished. + +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 ``afterthought'' or look like a screen shot of whatever the +authors's statistical software shows them. As will be argued later on, the +graphics that programs like \textsc{gnuplot} produce by default are of poor +quality. + +Creating informative graphics that help the reader and that fit together with +the main text is a difficult, lengthy process. +% \begin{itemize} -\item - Treat graphics as first-class citizens of your papers. They deserve - as much time and energy as the text does. - Indeed, the creation of graphics might deserve \emph{even more} time - than the writing of the main text since more attention will be paid - to the graphics and they will be looked at first. -\item - Plan as much time for the creation and revision of a graphic as you - would plan for text of the same size. -\item - Difficult graphics with a high information density may require even - more time. -\item - Very simple graphics will require less time, but most likely you do - not want to have ``very simple graphics'' in your paper, anyway; - just as you would not like to have a ``very simple text'' of the - same size. + \item Treat graphics as first-class citizens of your papers. They deserve + as much time and energy as the text does. Indeed, the creation of + graphics might deserve \emph{even more} time than the writing of the + main text since more attention will be paid to the graphics and they + will be looked at first. + \item Plan as much time for the creation and revision of a graphic as you + would plan for text of the same size. + \item Difficult graphics with a high information density may require even + more time. + \item Very simple graphics will require less time, but most likely you do + not want to have ``very simple graphics'' in your paper, anyway; just + as you would not like to have a ``very simple text'' of the same + size. \end{itemize} \subsection{Workflow for Creating a Graphic} -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 +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. Creating a graphics follows the same pattern: +% \begin{itemize} -\item - Decide on what the graphic should communicate. Make this a conscious - decision, that is, determine ``What is the graphic supposed to tell - the reader?'' -\item - Create an ``outline,'' that is, the rough overall ``shape'' of the - graphic, containing the most crucial elements. Often, it is - useful to do this using pencil and paper. -\item - Fill out the finer details of the graphic to create a first - draft. -\item - Revise the graphic repeatedly along with the rest of the paper. + \item Decide on what the graphic should communicate. Make this a + conscious decision, that is, determine ``What is the graphic supposed + to tell the reader?'' + \item Create an ``outline'', that is, the rough overall ``shape'' of the + graphic, containing the most crucial elements. Often, it is useful to + do this using pencil and paper. + \item Fill out the finer details of the graphic to create a first draft. + \item Revise the graphic repeatedly along with the rest of the paper. \end{itemize} - - \subsection{Linking Graphics With the Main Text} -Graphics can be placed at different places in a text. Either, they can -be inlined, meaning they are somewhere ``in the middle of the text'' -or they can be placed in stand-alone ``figures.'' Since printers (the -people) like to have their pages ``filled,'' (both for aesthetic and -economic reasons) stand-alone figures may traditionally be placed on -pages in the document far away from the main text that refers to -them. \LaTeX\ and \TeX\ tend to encourage this ``drifting away'' of -graphics for technical reasons. - -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. - -Quite differently, a stand-alone 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 stand-alone figures: +Graphics can be placed at different places in a text. Either, they can be +inlined, meaning they are somewhere ``in the middle of the text'' or they can +be placed in stand-alone ``figures''. Since printers (the people) like to have +their pages ``filled'', (both for aesthetic and economic reasons) stand-alone +figures may traditionally be placed on pages in the document far away from the +main text that refers to them. \LaTeX\ and \TeX\ tend to encourage this +``drifting away'' of graphics for technical reasons. + +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. + +Quite differently, a stand-alone 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 stand-alone figures: +% \begin{itemize} -\item - Stand-alone figures should have a caption than should make them - ``understandable by themselves.'' - - For example, suppose a graphic shows an example of the different - stages of a quicksort algorithm. Then the figure's caption should, - at the very least, inform the reader that ``The figure shows the - different stages of the quicksort algorithm introduced on page - xyz.'' and not just ``Quicksort algorithm.'' -\item - A good caption adds as much context information as possible. For - example, you could say: ``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\dots'' 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.) -\item - Reference the graphic in your main text as in ``For an example of - quicksort `in action,' see Figure~2.1 on page xyz.'' -\item - Most books on style and typography recommend that you do not use - abbreviations as in ``Fig.~2.1'' but write ``Figure 2.1.'' - - The main argument against abbreviations is that ``a period is too - valuable to waste it on an abbreviation.'' The idea is that a period - will make the reader assume that the sentence ends after ``Fig'' and - it takes a ``conscious backtracking'' to realize that the sentence - did not end after all. - - The argument in favor of abbreviations is that they save space. - - 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 ``Figure'' by - ``Fig.''\ is most unlikely to save even a single line in most - documents. I avoid abbreviations. + \item Stand-alone figures should have a caption than should make them + ``understandable by themselves''. + + For example, suppose a graphic shows an example of the different + stages of a quicksort algorithm. Then the figure's caption should, at + the very least, inform the reader that ``the figure shows the + different stages of the quicksort algorithm introduced on page xyz''. + and not just ``Quicksort algorithm''. + \item A good caption adds as much context information as possible. For + example, you could say: ``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\dots'' 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.) + \item Reference the graphic in your main text as in ``for an example of + quicksort `in action', see Figure~2.1 on page xyz''. + \item Most books on style and typography recommend that you do not use + abbreviations as in ``Fig.~2.1'' but write ``Figure~2.1''. + + The main argument against abbreviations is that ``a period is too + valuable to waste it on an abbreviation''. The idea is that a period + will make the reader assume that the sentence ends after ``Fig'' and + it takes a ``conscious backtracking'' to realize that the sentence + did not end after all. + + The argument in favor of abbreviations is that they save space. + + 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 ``Figure'' by + ``Fig.'' is most unlikely to save even a single line in most documents. + I avoid abbreviations. \end{itemize} - \subsection{Consistency Between Graphics and Text} -Perhaps the most common ``mistake'' people do when creating graphics -(remember that a ``mistake'' in design is always just ``ignorance'') -is to have a mismatch between the way their graphics look and the way -their text looks. - -It is quite common that authors use several different programs for -creating the graphics of a paper. An author might produce some plots -using \textsc{gnuplot}, a diagram using \textsc{xfig}, and include an -|.eps| 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 |[height=5cm]| when including graphics to scale them to -some ``nice size.'' - -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. -Readers and editors would not tolerate a text if it were written in +Perhaps the most common ``mistake'' people do when creating graphics (remember +that a ``mistake'' in design is always just ``ignorance'') is to have a +mismatch between the way their graphics look and the way their text looks. + +It is quite common that authors use several different programs for creating the +graphics of a paper. An author might produce some plots using \textsc{gnuplot}, +a diagram using \textsc{xfig}, and include an |.eps| 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 |[height=5cm]| when including graphics +to scale them to some ``nice size''. + +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. Readers and editors would not tolerate a text if it were written in this fashion, but with graphics they often have to. -To create consistency between graphics and text, stick to the -following guidelines: +To create consistency between graphics and text, stick to the following +guidelines: +% \begin{itemize} -\item - Do not scale graphics. - - This means that when generating graphics using an external program, - create them ``at the right size.'' -\item - Use the same font(s) both in graphics and the body text. -\item - Use the same line width in text and graphics. - - The ``line width'' for normal text is the width of the stem of - letters like T{}. For \TeX, this is usually - $0.4\,\mathrm{pt}$. However, some journals will not accept graphics - with a normal line width below $0.5\,\mathrm{pt}$. -\item - 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. - - 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 ``positive, go, - ok'' and red as ``alert, warning, action.'' + \item Do not scale graphics. + + This means that when generating graphics using an external program, + create them ``at the right size''. + \item Use the same font(s) both in graphics and the body text. + \item Use the same line width in text and graphics. + + The ``line width'' for normal text is the width of the stem of letters + like T{}. For \TeX, this is usually $0.4\,\mathrm{pt}$. However, some + journals will not accept graphics with a normal line width below + $0.5\,\mathrm{pt}$. + \item 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. + + 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 ``positive, go, + ok'' and red as ``alert, warning, action''. \end{itemize} Creating consistency when using different graphic programs is almost -impossible. For this reason, you should consider sticking to a single -graphics program. +impossible. For this reason, you should consider sticking to a single graphics +program. \subsection{Labels in Graphics} -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: - +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: +% \begin{itemize} -\item - 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. -\item - In addition to using the same fonts in text and graphics, you should - also use the same notation. For example, if you write $1/2$ in your - main text, also use ``$1/2$'' as labels in graphics, not - ``0.5''. A $\pi$ is a ``$\pi$'' and not ``$3.141$''. Finally, - $\mathrm e^{-\mathrm i \pi}$ is ``$\mathrm e^{-\mathrm i \pi}$'', - not ``$-1$'', let alone ``-1''. -\item - 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 labels of lines and text \emph{behind} the - labels. -\item - Labels should be ``in place.'' 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. -\item - Consider subduing ``unimportant'' labels using, for example, a gray - color. This will keep the focus on the actual graphic. + \item 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. + \item In addition to using the same fonts in text and graphics, you + should also use the same notation. For example, if you write $1/2$ in + your main text, also use ``$1/2$'' as labels in graphics, not + ``0.5''. A $\pi$ is a ``$\pi$'' and not ``$3.141$''. Finally, + $\mathrm e^{-\mathrm i \pi}$ is ``$\mathrm e^{-\mathrm i \pi}$'', not + ``$-1$'', let alone ``-1''. + \item 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 labels of lines and text \emph{behind} the + labels. + \item Labels should be ``in place''. 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. + \item Consider subduing ``unimportant'' labels using, for example, a gray + color. This will keep the focus on the actual graphic. \end{itemize} - \subsection{Plots and Charts} -One of the most frequent kind of graphics, especially in scientific -papers, are \emph{plots}. They come in a large variety, including -simple line plots, parametric plots, three dimensional plots, pie -charts, and many more. +One of the most frequent kind of graphics, especially in scientific papers, are +\emph{plots}. They come in a large variety, including simple line plots, +parametric plots, three dimensional plots, pie charts, and many more. -Unfortunately, plots are notoriously hard to get right. Partly, the -default settings of programs like \textsc{gnuplot} or Excel are to -blame for this since these programs make it very convenient to create -bad plots. +Unfortunately, plots are notoriously hard to get right. Partly, the default +settings of programs like \textsc{gnuplot} or Excel are to blame for this since +these programs make it very convenient to create bad plots. -The first question you should ask yourself when creating a plot is: -Are there enough data points to merit a plot? If the answer is ``not -really,'' use a table. +The first question you should ask yourself when creating a plot is: Are there +enough data points to merit a plot? If the answer is ``not really'', use a +table. -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 ``very good,'' -nine considered it ``good,'' ten ``ok,'' eight ``bad,'' and no one thought -that the seminar was ``very bad.'' +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 ``very good'', nine considered it ``good'', ten ``ok'', +eight ``bad'', and no one thought that the seminar was ``very bad''. A simple way of summing up this information is the following table: @@ -324,10 +287,9 @@ A simple way of summing up this information is the following table: \end{tabular} \bigskip -What the lecturer did was to visualize the data using a 3D bar -diagram. It looked like this (except that in reality the numbers -where typeset using some extremely low-resolution bitmap font and -were near-unreadable): +What the lecturer did was to visualize the data using a 3D bar diagram. It +looked like this (except that in reality the numbers where typeset using some +extremely low-resolution bitmap font and were near-unreadable): \bigskip \par @@ -353,72 +315,58 @@ were near-unreadable): \end{tikzpicture} \bigskip -Both the table and the ``plot'' have about the same size. If your first -thought is ``the graphic looks nicer than the table,'' try to answer -the following questions based on the information in the table or in -the graphic: +Both the table and the ``plot'' have about the same size. If your first thought +is ``the graphic looks nicer than the table'', try to answer the following +questions based on the information in the table or in the graphic: +% \begin{enumerate} -\item - How many participants where there? -\item - How many participants returned the feedback form? -\item - What percentage of the participants returned the feedback form? -\item - How many participants checked ``very good''? -\item - What percentage out of all participants checked ``very good''? -\item - Did more than a quarter of the participants check ``bad'' or ``very bad''? -\item - What percentage of the participants that returned the form checked ``very good''? + \item How many participants where there? + \item How many participants returned the feedback form? + \item What percentage of the participants returned the feedback form? + \item How many participants checked ``very good''? + \item What percentage out of all participants checked ``very good''? + \item Did more than a quarter of the participants check ``bad'' or ``very + bad''? + \item What percentage of the participants that returned the form checked + ``very good''? \end{enumerate} Sadly, the graphic does not allow us to answer \emph{a single one of these - questions}. The table answers all of them directly, except for the last -one. In essence, the information density of the graphic is very -close to 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. -Here is the list of things that went wrong with the 3D-bar diagram: +questions}. The table answers all of them directly, except for the last one. In +essence, the information density of the graphic is very close to 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. Here is the list of things +that went wrong with the 3D-bar diagram: +% \begin{itemize} -\item - The whole graphic is dominated by irritating background lines. -\item - It is not clear what the numbers at the left mean; presumably - percentages, but it might also be the absolute number of - participants. -\item - The labels at the bottom are rotated, making them hard to read. - - (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.) -\item - The third dimension adds complexity to the graphic without adding - information. -\item - The three dimensional setup makes it much harder to gauge the height - of the bars correctly. Consider the ``bad'' 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. -\item - It is impossible to tell which numbers are represented by the - bars. Thus, the bars needlessly hide the information these bars are - all about. -\item - What do the bar heights add up to? Is it 100\% or 60\%? -\item - Does the bar for ``very bad'' represent 0 or~1? -\item - Why are the bars blue? + \item The whole graphic is dominated by irritating background lines. + \item It is not clear what the numbers at the left mean; presumably + percentages, but it might also be the absolute number of + participants. + \item The labels at the bottom are rotated, making them hard to read. + + (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.) + \item The third dimension adds complexity to the graphic without adding + information. + \item The three dimensional setup makes it much harder to gauge the + height of the bars correctly. Consider the ``bad'' 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. + \item It is impossible to tell which numbers are represented by the + bars. Thus, the bars needlessly hide the information these bars are + all about. + \item What do the bar heights add up to? Is it 100\% or 60\%? + \item Does the bar for ``very bad'' represent 0 or~1? + \item Why are the bars blue? \end{itemize} -You might argue that in the example the exact numbers are not -important for the graphic. The important things is the ``message,'' -which is that there are more ``very good'' and ``good'' ratings than -``bad'' and ``very bad.'' However, to convey this message either use a -sentence that says so or use a graphic that conveys this message more -clearly: +You might argue that in the example the exact numbers are not important for the +graphic. The important things is the ``message'', which is that there are more +``very good'' and ``good'' ratings than ``bad'' and ``very bad''. However, to +convey this message either use a sentence that says so or use a graphic that +conveys this message more clearly: \medskip \par @@ -455,15 +403,14 @@ clearly: \end{tikzpicture} \bigskip -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 ``see'' that there are more good or very good ratings -than bad ones. One can also ``see'' that the number of people who gave -no rating at all is not negligible, which is quite common for feedback -forms. +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 +``see'' that there are more good or very good ratings than bad ones. One can +also ``see'' that the number of people who gave no rating at all is not +negligible, which is quite common for feedback forms. -Charts are not always a good idea. Let us look at an example -that I redrew from a pie chart in \emph{Die Zeit}, June 4th, 2005: +Charts are not always a good idea. Let us look at an example that I redrew from +a pie chart in \emph{Die Zeit}, June 4th, 2005: \bigskip \par @@ -557,168 +504,148 @@ that I redrew from a pie chart in \emph{Die Zeit}, June 4th, 2005: \end{scope} \end{tikzpicture} -This graphic has been redrawn in \tikzname, but the original looks -almost exactly the same. - -At first sight, the graphic looks ``nice and informative,'' but there -are a lot of things that went wrong: +This graphic has been redrawn in \tikzname, but the original looks almost +exactly the same. +At first sight, the graphic looks ``nice and informative'', but there are a lot +of things that went wrong: +% \begin{itemize} -\item - The chart is three dimensional. However, the shadings add - nothing ``information-wise,'' at best, they distract. -\item - In a 3D-pie-chart the relative sizes are very strongly - distorted. For example, the area taken up by the gray color of ``Braunkohle'' - is larger than the area taken up by the green color of - ``Kernenergie'' \emph{despite the fact that the percentage of - Braunkohle is less than the percentage of Kernenergie}. -\item - The 3D-distortion gets worse for small areas. The area of - ``Regenerative'' somewhat larger than the area of ``Erdgas.'' - The area of ``Wind'' is slightly smaller than the area of - ``Mineral\"olprodukte'' \emph{although the percentage of Wind is - nearly three times larger than the percentage of - Mineral\"olprodukte.} - - In the last case, the different sizes are only partly due to - distortion. The designer(s) of the original graphic have also made - the ``Wind'' slice too small, even taking distortion into - account. (Just compare the size of ``Wind'' to ``Regenerative'' in - general.) -\item - 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. - - Coal as an energy source is split up into two slices: one for - ``Steinkohle'' and one for ``Braunkohle'' (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. - - 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, ``Regenerative'' - and ``Wind'' are very closely linked. -\item - The color coding of the graphic follows no logical pattern at - all. Why is nuclear energy green? Regenerative energy is light blue, - ``other sources'' are blue. It seems more like a joke that the area - for ``Braunkohle'' (which literally translates to ``brown coal'') is - stone gray, while the area for ``Steinkohle'' (which literally - translates to ``stone coal'') is brown. -\item - The area with the lightest color is used for ``Erdgas.'' This area - stands out most because of the brighter color. However, for this - chart ``Erdgas'' is not really important at all. + \item The chart is three dimensional. However, the shadings add nothing + ``information-wise'', at best, they distract. + \item In a 3D-pie-chart the relative sizes are very strongly distorted. + For example, the area taken up by the gray color of ``Braunkohle'' is + larger than the area taken up by the green color of ``Kernenergie'' + \emph{despite the fact that the percentage of Braunkohle is less than + the percentage of Kernenergie}. + \item The 3D-distortion gets worse for small areas. The area of + ``Regenerative'' somewhat larger than the area of ``Erdgas''. The + area of ``Wind'' is slightly smaller than the area of + ``Mineral\"olprodukte'' \emph{although the percentage of Wind is + nearly three times larger than the percentage of + Mineral\"olprodukte.} + + In the last case, the different sizes are only partly due to + distortion. The designer(s) of the original graphic have also made + the ``Wind'' slice too small, even taking distortion into + account. (Just compare the size of ``Wind'' to ``Regenerative'' in + general.) + \item 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. + + Coal as an energy source is split up into two slices: one for + ``Steinkohle'' and one for ``Braunkohle'' (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. + + 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, ``Regenerative'' + and ``Wind'' are very closely linked. + \item The color coding of the graphic follows no logical pattern at all. + Why is nuclear energy green? Regenerative energy is light blue, + ``other sources'' are blue. It seems more like a joke that the area + for ``Braunkohle'' (which literally translates to ``brown coal'') is + stone gray, while the area for ``Steinkohle'' (which literally + translates to ``stone coal'') is brown. + \item The area with the lightest color is used for ``Erdgas''. This area + stands out most because of the brighter color. However, for this + chart ``Erdgas'' is not really important at all. \end{itemize} -Edward Tufte calls graphics like the above ``chart junk.'' (I am happy -to announce, however, that \emph{Die Zeit} has stopped using 3D pie -charts and their information graphics have got somewhat better.) +% +Edward Tufte calls graphics like the above ``chart junk''. (I am happy to +announce, however, that \emph{Die Zeit} has stopped using 3D pie charts and +their information graphics have got somewhat better.) Here are a few recommendations that may help you avoid producing chart junk: +% \begin{itemize} -\item - Do not use 3D pie charts. They are \emph{evil}. -\item - Consider using a table instead of a pie chart. -\item - Do not apply colors randomly; use them to direct the readers's - focus and to group things. -\item - Do not use background patterns, like a crosshatch or diagonal - lines, instead of colors. They distract. Background patterns in - information graphics are \emph{evil}. + \item Do not use 3D pie charts. They are \emph{evil}. + \item Consider using a table instead of a pie chart. + \item Do not apply colors randomly; use them to direct the readers's + focus and to group things. + \item Do not use background patterns, like a crosshatch or diagonal + lines, instead of colors. They distract. Background patterns in + information graphics are \emph{evil}. \end{itemize} - \subsection{Attention and Distraction} -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. - -Good typography (like good organization) is something you do -\emph{not} notice. The job of typography is to make reading the text, -that is, ``absorbing'' 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. - -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 ``going on'' 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. - -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. - -The two principles ``avoid distractions'' and ``steer attention'' also -apply to graphics. When you design a graphic, you should eliminate -everything that will ``distract the eye.'' At the same time, you -should try to actively help the reader ``through the graphic'' by -using fonts/colors/line widths to highlight different parts. +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. + +Good typography (like good organization) is something you do \emph{not} notice. +The job of typography is to make reading the text, that is, ``absorbing'' 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. + +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 ``going on'' 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. + +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. + +The two principles ``avoid distractions'' and ``steer attention'' also apply to +graphics. When you design a graphic, you should eliminate everything that will +``distract the eye''. At the same time, you should try to actively help the +reader ``through the graphic'' by using fonts/colors/line widths to highlight +different parts. Here is a non-exhaustive list of things that can distract readers: +% \begin{itemize} -\item - Strong contrasts will always be registered first by the eye. For - example, consider the following two grids: - - \medskip\par - \begin{tikzpicture}[x=40pt,y=40pt] - \draw[step=10pt,gray] (0,0) grid +(1,1); - \draw[step=2pt] (2,0) grid +(1,1); - \end{tikzpicture} - - \medskip - Even though the left grid comes first in English 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 ``places'' adding to the - overall contrast in the right grid. - - 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. -\item - 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. - - Do not use different dashing patterns to differentiate curves in - plots. You lose data points this way and the eye is not - particularly good at ``grouping things according to a dashing - pattern.'' The eye is \emph{much} better at grouping things - according to colors. -\item - 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. -\item - Background images and shadings distract and only seldomly add - anything of importance to a graphic. -\item - Cute little clip arts can easily draw attention away from the - data. + \item Strong contrasts will always be registered first by the eye. For + example, consider the following two grids: + + \medskip\par + \begin{tikzpicture}[x=40pt,y=40pt] + \draw[step=10pt,gray] (0,0) grid +(1,1); + \draw[step=2pt] (2,0) grid +(1,1); + \end{tikzpicture} + + \medskip + Even though the left grid comes first in English 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 ``places'' adding to the overall contrast in the right + grid. + + 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. + \item 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. + + Do not use different dashing patterns to differentiate curves in + plots. You lose data points this way and the eye is not particularly + good at ``grouping things according to a dashing pattern''. The eye + is \emph{much} better at grouping things according to colors. + \item 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. + \item Background images and shadings distract and only seldomly add + anything of importance to a graphic. + \item Cute little clip arts can easily draw attention away from the data. \end{itemize} |