Interactivity in producing graphs challenges for producers and data users

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1 Federal Department of Home Affairs FDHA Federal Statistical Office FSO Output Services Division Daniel von Burg, Statistics Switzerland with thanks to Armin Grossenbacher, Pierre-Alain Baeriswyl and Alain Nadeau Interactivity in producing graphs challenges for producers and data users OECD Seminar on Innovative Approaches to Turning Statistics into Knowledge, May , Stockholm We all agree: Graphs are an excellent fundament to disseminate and to help understand statistics. But when making visualizations available we have to cope with three principle challenges: Statistical literacy, accessibility and sustainable production. First challenge: is everybody able to understand graphs? This example by Ch. J. Minard from 1869 is probably the best statistical graphic ever drawn (E. Tufte). One sees it in almost every book on visualization. Though its content is very complex it is easy to read. The main message is almost jumping into the eye. Design and weight of all elements are perfect. How does it work? What about statistical or better graphical literacy? Federal Statistical Office FSO Daniel von Burg Espace de l'europe 10, CH-2010 Neuchâtel Phone , Fax

2 Today bad proportions or bad labeling are common. Everybody knows examples of bad visualizations under the term «How to lie with statistics?» e.g. an axis that does not start with zero. In the example below even the time axis does not have the same interval. Such errors can easily be discovered, even with the help of checklists. Even visualization software can avoid them, if the tool is well designed and properly operated. Production of Cars in Great Britain, 1972 to 1988 (in mio.) * estimation in: Walter Krämer 1991 «So lügt man mit Statistik» But errors in statistical concepts are of much higher importance. To avoid these traps one needs sound knowledge in scientific concepts. Statistical facts and figures are very important in the political discussion. One has to define the indicator according to the statement to be made. Here is an example of recent date using more or less the same absolute figures and it affects Sweden and Switzerland: Ad reproduced in many ads in Swiss journals A visualization of official statistics, published by «St.Galler Tagblatt», April To compare countries of different size one has to divide the absolute number by the population. Well, the ranking of Switzerland in these two visualizations of the same subject is completely different, according to the population definition used in the quotient. The raw number of citizenships granted is defined as number of citizenships awarded as a percentage of the foreign permanent population (diagram on the right). If you take the total resident population instead, the bias of the proportion of the foreign population living in the country will be of higher importance than the influence of the policy on granting citizenship (diagram on the left). 2/6

3 So it is a good decision if authors who are statistical experts in their domain may express themselves in graphical language and therefore have a good visualization instrument in their daily toolbox. On the other hand we cannot expect that authors actually understand the fundamental principles of graphical design. They need to use templates with only a handful of fields to fill in all the information to be shown in a chart. That is the reason why we asked our developer to seamlessly integrate JFreeChart into our Web CMS. How the data is integrated into the Web CMS. Copy & paste from different sources (mainly Excel) is very easy. Second challenge: access for all and tailored information Web technologies allow handicapped people equal opportunities to participate in public life. But be careful: about 8% of the male and 1% of the female population is affected by color blindness (Wikipedia). 1.4% of the people in Switzerland are affected by visual impairment (Swiss Health Survey, 2002). So visualizations may exclude a considerable proportion of the users of official statistics. For color deficits it is very easy to avoid mistakes. Just choose colors that are well defined and do not display colors with almost the same brightness values close together. This also helps people who may only print the chart in black and white. 3/6

4 Predefined color combinations ensure homogeneity in all charts drawn for the web site. They were developed by a color-blind person and have been used successfully in print publications for many years. Blind people may not be able to read a chart at all. Today, tools are not able to present data in an accessible way. We address this request by also offering the data in a table or offering the excel file for download close to the chart. The same excel file used to build the chart is used for publication and stored in a central database. This is a big advantage for researchers or journalists too if they can easily access the data behind the chart (sometimes with some additional remarks, which only interest specific target groups). Many possibilities to fine-tune the chart are also offered. Y axis range and interval Additional information like axis title, %-sign, etc. Hide items of the statistic Legend properties Third challenge: sustainable production of graphs Most charts need to be updated regularly. So we need to realize smooth workflows. Invoking specialists creates a notorious bottleneck since visualization requests often come in waves. About four fifths of the demands are a matter of routine and can be automated and delegated to the authors. They can accomplish this task with our CMS charting component. 4/6

5 Visualizations made by the authors for the web may also be used for reports and other print publications. But cross media ability is a big challenge because paper (or PDF) may carry about four times as much information as the same surface on a screen. We need to be able to enlarge (print web) resp. reduce (web print) the size of a chart. Therefore we have the possibility to export the chart from the Web CMS as an SVG file (XML application) for print usage. The vector data can be scaled with ease or combined with other graphical elements to produce an eye-catching diagram. Adobe Illustrator is able to import SVG files and convert it to a PDF for seamless use in print publications. Graphs produced for web or print are stored in a central database the media library. In order to improve quality we need smooth but flexible workflows around digital assets. That means we must have close links to the central data storage and are able to treat different print and web needs in one request one update enables multiple use. Three different dimensions of quality are improved that way: First, we are avoiding errors caused by any interface when converting information because it is only made once and not individually for each service. Secondly, we can learn from our experiences and use them for continuous improvement of our services. Enabling authors to create high quality graphs with the CMS Charting Component, reusing graphs out of the media library and in a cross media environment helps us in bringing statistical results even faster to our customers. This is a third dimension of quality becoming nowadays more and more important where information is disseminated with the speed of light. Creating graphs: What about interactivity on the user side? What does the term «interactivity» signify? The FSO already produces interactive maps in Flash. Such visualizations choosing predefined indicators and seeing the exact figures when the mouse is hovering above the data point is only interactive on the level of the human-machine interface. The main goal of this kind of interactivity is to cope with the limited space available on screen. The data and the approach to it are static. All visualizations based on static data can be improved by the producer of official data. He knows about all the problems inherent to the data and therefore can cope easily with the three challenges mentioned before. 5/6

6 Interactivity also means that users may create their own visualizations with official data. There is plenty of it available on the internet. But does it fit into an easy-to-use and safe interface? The FSO ensures accessibility to a large audience by offering its most important data in a centralized data library, where users are presented with excel files in a user-friendly way. This collection of tables and other elements, such as maps and publications, is called the «Statistical Encyclopedia». But for users today it is not possible to make graphs out of it automatically. For better reading of the data the internal structure of the files are very different. If we use analytic tools instead to access the raw data, this is what we might get: It is very difficult to represent the logical structure of the data in a data warehouse and to extract it to a chart automatically. Today, this can be made in a more user-friendly way by a human author or editor. When there are good templates available it can be done very quickly. There is also the need for meta-information. Every statistical indicator has its desired effects and side effects. To check the message before publishing the visualization any user may study the documentation about the concepts and methods of data collection. This is very clearly stated in paragraph 3 of the UN fundamental principles of official statistics. Take the example of the pharma industry. The patient information leaflet is regulated by law. For leading companies a little additional effort on its content is included in the marketing budget to make sure the patient customer understands what is written. 6/6