1Overview of InfoVisCS 4460/7450 - Information VisualizationJan. 14, 2010John StaskoSpring 2010 CS 4460/7450 2Exercise• Get out pencil and paper2Spring 2010 CS 4460/7450 3Data Explosion• Society is more complex There simply is more “stuff”• Computers, internet and web give people access to an incredible amount of data news, sports, financial, purchases, etc...How Much Data? (1)• Estimated info added to digital universe each year will soon approach 1 ZB (zettabyte)* 1000000000000000000000 (1021)bytes From: http://www.emc.com/digital_universe viewed December 8, 2008Spring 2010 CS 4460/7450 4*But only half that goes to my email inbox3How Much Data? (2)• 6 million FedEx transactions per day http://www.fedex.com/us/about/today/companies/corporation/facts.html• Average of 98 million Visa credit-card transactions per day in 2005 http://www.corporate.visa.com/md/nr/press278.jsp• Average of 5.4 petabytes of data crosses AT&T‟s network per day http://att.sbc.com/gen/investor-relations?pid=5711• Average of 610 to 1110 billion e-mails worldwide per year (based on estimates in 2000) http://www2.sims.berkeley.edu/research/projects/how-much-info/internet.htmlSpring 2010 CS 4460/7450 5Slide courtesy Jim ThomasSpring 2010 CS 4460/7450 6Data Overload• Confound: How to make use of the data How do we make sense of the data? How do we harness this data in decision-making processes? How do we avoid being overwhelmed?4Spring 2010 CS 4460/7450 7The Challenge• Transform the datainto information(understanding, insight) thus making it useful to peopleSpring 2010 CS 4460/7450 8The ProblemDataHow?Data TransferWeb,Books,Papers, Game scores, Scientific data,Biotech,ShoppingPeopleStock/financeNewsVision: 100 MB/sEars: <100 b/sTelepathyHaptic/tactileSmellTasteTwo slides courtesyof Chris North5Spring 2010 CS 4460/7450 9Human Vision• Highest bandwidth sense• Fast, parallel• Pattern recognition• Pre-attentive• Extends memory and cognitive capacity(Multiplication test)• People think visuallyImpressive. Lets use it!Some Examples• Why visualization helps…Spring 2010 CS 4460/7450 106Spring 2010 CS 4460/7450 11Which cereal has the most/least potassium?Is there a relationship between potassium and fiber?If so, are there any outliers?Which manufacturer makes the healthiest cereals?Questions:Spring 2010 CS 4460/7450 12PotassiumFiber7Spring 2010 CS 4460/7450 13Even Tougher?• What if you could only see one cereal‟s data at a time? (e.g. some websites)• What if I read the data to you?Spring 2010 CS 4460/7450 14Another Illustrative Example8Spring 2010 CS 4460/7450 15Four Data Sets• Mean of the x values = 9.0• Mean of the y values = 7.5• Equation of the least-squared regression line is: y = 3 + 0.5x• Sums of squared errors (about the mean) = 110.0• Regression sums of squared errors (variance accounted for by x) = 27.5• Residual sums of squared errors (about the regression line) = 13.75• Correlation coefficient = 0.82• Coefficient of determination = 0.67http://astro.swarthmore.edu/astro121/anscombe.htmlSpring 2010 CS 4460/7450 16The Data Sets9Spring 2010 CS 4460/7450 17The Values1 2 3 410.0, 8.04 10.0,9.14 10.0, 7.46 8.0, 6.58 8.0, 6.95 8.0,8.14 8.0, 6.77 8.0, 5.7613.0, 7.58 13.0,8.74 13.0,12.74 8.0, 7.719.0, 8.81 9.0,8.77 9.0, 7.11 8.0, 8.84 11.0, 8.33 11.0,9.26 11.0, 7.81 8.0, 8.4714.0, 9.96 14.0,8.10 14.0, 8.84 8.0, 7.046.0, 7.24 6.0,6.13 6.0, 6.08 8.0, 5.254.0, 4.26 4.0,3.10 4.0, 5.39 19.0,12.5012.0,10.84 12.0,9.13 12.0, 8.15 8.0, 5.567.0, 4.82 7.0,7.26 7.0, 6.42 8.0, 7.915.0, 5.68 5.0,4.74 5.0, 5.73 8.0, 6.89Spring 2010 CS 4460/7450 18Exercise Redux• Let‟s check what you did…• People work differently10Spring 2010 CS 4460/7450 19Visualization• Definition “The use of computer-supported, interactive visual representations of data to amplify cognition.”From [Card, Mackinlay Shneiderman „98]Spring 2010 CS 4460/7450 20Visualization• Often thought of as process of making a graphic or an image• Really is a cognitive process Form a mental image of something Internalize an understanding• “The purpose of visualization is insight, not pictures” Insight: discovery, decision making, explanation11Spring 2010 CS 4460/7450 21Main Idea• Visuals help us think Provide a frame of reference, a temporary storage area• Cognition  Perception• Pattern matching• External cognition aid Role of external world in thinking and reasonLarkin & Simon ‟87Card, Mackinlay, Shneiderman „98 Spring 2010 CS 4460/7450 22When to Apply?• Many other techniques for data analysis Data mining, DB queries, machine learning…• Visualization most useful in exploratory data analysis Don‟t know what you‟re looking for Don‟t have a priori questions Want to know what questions to ask12Spring 2010 CS 4460/7450 23Part of our Culture• “I see what you‟re saying”• “Seeing is believing”• “A picture is worth a thousand words”Spring 2010 CS 4460/7450 24OverviewVisualization“Data visualization”ScientificvisualizationInformationvisualization13Spring 2010 CS 4460/7450 25Scientific Visualization• Primarily relates to and represents something physical or geometric Often 3-D ExamplesAir flow over a wingStresses on a girderTorrents inside a tornadoOrgans in the human bodyMolecular bondingNot the focus of this classSpring 2010 CS 4460/7450 26Information Visualization• What is “information”? Items, entities, things which do not have a direct physical correspondence Notion of abstractness of the entities is important too Examples: baseball statistics, stock trends, connections between criminals, car attributes...14Spring 2010 CS 4460/7450 27Information Visualization• What is “visualization”? The use of computer-supported, interactive visual representations of data to amplify cognition.From [Card, Mackinlay Shneiderman „98]Spring 2010 CS 4460/7450 28Information Visualization• Components: Taking items without a direct physical correspondence and mapping them to a 2-D or 3-D physical space. Giving information a visual representation that is useful for analysis and decision-making15Purpose• Two main uses of infovis Analysis – Understand your data better and act upon that understanding Presentation – Communicate and inform others more