3/8/16

1

UncertaintyinBarGraphs

ReadingforTuesday(pickone)

•  "ErrorBarsConsideredHarmful:ExploringAlternateEncodingsforMeanandError",Correll&Gleicher,TVCG2014

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2

•  Whatis“InferenOalstaOsOcs”?•  Whatis“Null-hypothesissignificancetesOng”?•  OthershavesuggestedproblemswitherrorbarvisualizaOon,butno

one(“toourknowledge”)hasdonearigorouscomparaOvestudyyet•  Outliersaremorememorable,resulOnginbiasofourpercepOonofthe

distribuOon/mean/stddev–  Visualizinguncertaintywillhelpcorrectthisbias

•  Peopleuseerrorbarsindifferentways(mightnotbelabeledorlabeledfarawayincapOonortext)–  Range,95%,80%,stderror,stddev,etc.–  Dependingontheuse,differentheurisOcsnecessaryforvisualanalysis/

inference–  CommonpracOce:addglyph(*)toindicatesomethingisstaOsOcally

significant•  GraphicallysalientfeaturesofthedifferentopOonshaveimpacton

interpretaOon•  Standardshavedeveloped,beendefinedindifferentdisciplines

–  ExaminedallpublicaOonsinrecentconference,counOng#thatusedifferentvariantsoferrorbars

•  CanpotenOallyuseany“visualchannel”(transparency,width)toexpressuncertainty–  Violinplotsnotwidelyused…goodchoice(?)chancetointruduceanewstandard

•  Goals:–  VisualizeerrorwithoutlosingvisualizaOonofmean–  Usersshoulddrawproperinferencesfromdata–  ConOnuousbeherthanbinaryencoding(allowsdifferentuses)–  Probablyshouldbesymmetric

•  WhatisthebestchoiceforlimiteddisplayresoluOon?(equivlotsofdataononeplot?)

•  Transparency:lowsaturaOonisassociatedwithlowconfidence/uncertainty–  Gammaproblem?

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3

•  Onesamplejudgement(reddotinquesOon)•  Onesample+textjudgement(quesOonincapOon)

•  Twosamplejudgement(?)

•  MechanicalTurk

•  ImpactofvisualizaOonchoiceforPredicOon(thisstudy)vs.Decisionmaking(futurework)

•  WhataboutAestheOcs?Preference?

BeanplotvsViolinplot

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4

GammaCorrecOon

hhp://xahlee.info/img/what_is_gamma_correcOon.html

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5

ReadingforTuesday(pickone)

•  "VisualEncodingsofTemporalUncertainty:AComparaOveUserStudy",Gschwandtner,Bogl,Federico,&Miksch,TVCG2016

JosephPriestlyvisualizaOon(1765)

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6

PertChart(USNavy1950)

hhp://www.vistage.com/resource/how-to-keep-it-projects-on-schedule-part-2-pert-charts/

Sopodiagram

hhps://eagereyes.org/techniques/sets-of-possible-occurrences

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7

Ganhchart

hhps://en.wikipedia.org/wiki/Ganh_chart#/media/File:GanhChartAnatomy.svg

•  HowtomodelOmeinstants,intervals,spans

•  Wrihenexamplesofuncertaintyforeacharenotcompletelyclear(?)

•  Userstudy– TypesofquesOonsseemprehycomplicated(comparedtootheruserstudies)

– AlluserswerestudentsinavisualizaOonclass(trainedinvisualobservaOon,researcherbiases?)

– Someusersgotconfusedandmadetrivalmistakes(startvs.endearliestvs.latest)

– ResearchersadmitsomequesOonswerebadlyphrased

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•  Paperwasdetailed&reproducible•  Goodsizeforuserstudy(73)•  CitaOonusingnumberonlyishardertoreadthatcitaOonwithauthorname.

•  Surprised(bothauthorsandusasreaders)thatviolinplotsdidn’tperformaswellasgradientplots

•  J.BerOn.Semiologyofgraphics:diagrams,networks,maps(translatedbyWilliamJ.Berg).UniversityofWisconsinPress,1967/1983.–  definedthesesevenvisualvariablesforvisualrepresentaOons:locaOon,size,colorhue,colorvalue,grain,orientaOon,andshape

•  J.L.Morrison.AtheoreOcalframeworkforcartographicgeneralizaOonwiththeemphasisontheprocessofsymbolizaOon.InternaOonalYearbookofCartography,14:115–127,1974.

•  A.M.MacEachren.VisualizinguncertaininformaOon.CartographicPerspecOves,(13):10–19,1992.

•  A.M.MacEachren.Howmapswork:representaOon,visualizaOon,anddesign.GuilfordPress,1995.

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9

ReadingforFriday

•  “RepresenOngUncertaintyinGraphEdges:AnEvaluaOonofPairedVisualVariables”Guo,Huang,andLaidlaw,IEEETCVG2015

AlternateReadingforFriday:

•  “SiOngObserversonTerrain”WmRandolphFranklin

3/8/16

10

InclassOmeforHomework6…•  Teamupwithanotherstudent,someonesi0ngonthe

oppositesideoftheroom,someoneyoudidnotknowbeforeclassandhaven’tworkedwithyet

•  Comeupwithasimple,Ome-baseddataset–  Omespentinatypicalweekon

sleep/class/homework/eat/sports/tv–  linesofcodewrihenduringyourOmeatRPI

indifferentprogramminglanguages(python,c++,java,etc)–  moneyspentoveratypicalmonth/yearon

tuiOon/apartment/food/travel/clothing/movies–  ?

•  Youmaywanttoidealizeorexaggeratethesimilari@esanddifferencesinthedataforthe2teammembers

•  First,drawthedatausinga“boring”barorstackedbargraphoverOme(2separateplots,1foreachperson,usingthesamedesign/colors)

•  Then,sketchastreamgraphversionofthisdata(also2separateplots,1foreachperson,usingthesamedesign/colors)