Encyclopedia of Computer Science and Technology

240 information retrievalinvasion of Russia with the diminishing size of the Frenchforces. These early examples coincided with a time whenindustrial society was becoming increasingly complex andpopulous, and both government and business needed newways to visualize statistics. Other products to which informationdesign contributes became important in the followingcentury: traffic and transit signs, product warninglabels, and product manuals, to name a few.Some of the basic considerations for information designinclude:• effectiveness at presenting relevant information• selection and arrangement of information• balance of attractiveness and clarity• proper use of the medium (size, materials, etc.)Of course the designer has additional constraints, such asthe purpose of the design (advertising, product documentation,report, etc.), policies of the client, any applicable regulations(such as for warning labels), and so on.From Physical to DigitalMoving from the world of print to the Web brings newresources and challenges to the information designer. Webdesign has many advantages over print—powerful layouttools and perhaps templates, the availability of animationor other effects, the ability to adapt to different audiences,and, above all, interactivity. However, each of these featuresbrings additional choices—not only font and text size,but background, use of images, whether to include animation(such as Flash), and how to design clear and easy-touseforms and other interactive features. Further, designsmay have to adapt to a variety of platforms (large desktopscreens, laptops, PDAs, and mobile devices) and providefor users who have visual impairments or other disabilities(for more, see Web page design). For information displaysdesigned to provide “at a glance” summaries and alertsabout problems, see digital dashboard.Although these concerns may seem far afield from theclassic principles of graphic design, they actually representtechnological extensions of them. It is easy to get lost in theparticulars of designing, for example, Web pages showingstatistical charts, without having thought about whetherthe charts themselves show information clearly and accuratelyin the scales and proportions used.Further ReadingDigital Web Magazine. Available online. URL: http://www.digitalweb.com/.Accessed September 23, 2007.Few, Stephen. Information Dashboard Design: The Effective VisualCommunication of Data. Sebastapol, Calif.: O’Reilly Media,2006.Information Design Journal. John Herndon, Va.: Benjamins PublishingCompany, 1979. Free sample available online. URL:http://www.benjamins.com/cgi-bin/t_bookview.cgi?bookid=IDJDD%2012%3A1. Accessed September 23, 2007.Lipton, Ronnie. The Practical Guide to Information Design. NewYork: Wiley, 2007.Lõwgren, Jonas, and Erik Stolterman. Thoughtful InteractionDesign: A Design Perspective on Information Technology. 2nded. Cambridge, Mass.: MIT Press, 2007.Tufte, Edward R. Envisioning Information. Cheshire, Conn.: GraphicsPress, 1990.———. The Visual Display of Quantitative Information. 2nd ed.Cheshire, Conn.: Graphics Press, 2001.information retrievalWhile much attention is paid by system designers to therepresentation, storage and manipulation of information inthe computer, the ultimate value of information processingsoftware is determined by how well it provides for the effectiveretrieval of that information. The quality of retrieval isdependent on several factors: hardware, data organization,search algorithms, and user interface.At the hardware level, retrieval can be affected by theinherent seek time of the device upon which the data isstored (such as a hard disk), the speed of the central processor,and the use of temporary memory to store data that islikely to be requested (see cache). Generally, the larger thedatabase and the amount of data that must be retrieved tosatisfy a request, the greater is the relative importance ofhardware and related system considerations.Data organization includes the size of data records andthe use of indexes on one or more fields. An index is a separatefile that contains field values (usually sorted alphabetically)and the numbers of the corresponding records. Withindexing, a fast binary search can be used to match theuser’s request to a particular field value and then the appropriaterecord can be read (see hashing).There is a tradeoff between storage space and ease ofretrieval. If all data records are the same length, randomaccess can be used; that is, the location of any record can becalculated essentially by multiplying the record’s sequencenumber by the fixed record length. However, having a fixedrecord size means that records with shorter data fields mustbe “padded,” wasting disk space. Given the low cost of diskstorage today, space is generally less of a consideration.The search algorithms used by the program can alsohave a major impact on retrieval speed (see sorting andsearching). As noted, if a binary search can be done againsta sorted list of fields or records, the desired record can befound in only a few comparisons. At the opposite extreme,if a program has to move sequentially through a wholedatabase to find a matching record, the average number ofcomparisons needed will be half the number of records inthe file. (Compare looking up something in a book’s indexto reading through the book until you find it.)Real-world searching is considerably more complex,since search requests can often specify conditions suchas “find e-commerce but not amazon.com” (see Booleanoperators). Searches can also use wildcards to find a wordstem that might have several different possible endings,proximity requirements (find a given word within so manywords of another), and other criteria. Providing a robust setof search options enables skilled searchers to more preciselyfocus their searches, bringing the number of results downto a more manageable level. The drawback is that complexsearch languages result in more processing (often severalintermediate result sets must be built and internally com-