ThesearetheproceedingsofthefourthbiennialconferenceintheIntelligentData Analysisseries. TheconferencetookplaceinCascais,Portugal,13¿15September 2001. Thethemeofthisconferenceseriesistheuseofcomputersinintelligent waysindataanalysis,includingtheexplorationofintelligentprogramsfordata analysis. Dataanalytictoolscontinuetodevelop,drivenbythecomputerrevo- tion. Methodswhichwouldhaverequiredunimaginableamountsofcomputing power,andwhichwouldhavetakenyearstoreachaconclusion,cannowbe appliedwitheaseandvirtuallyinstantly. Suchmethodsarebeingdevelopedby avarietyofintellectualcommunities,includingstatistics,arti?cialintelligence, neuralnetworks,machinelearning,datamining,andinteractivedynamicdata visualization. Thisconferenceseriesseekstobringtogetherresearchersstudying theuseofintelligentdataanalysisinthesevariousdisciplines,tostimulate- teractionsothateachdisciplinemaylearnfromtheothers. Soastoencourage suchinteraction,wedeliberatelykepttheconferencetoasingletrackmeeting. Thismeantthat,ofthealmost150submissionswereceived,wewereableto selectonly23fororalpresentationand16forposterpresentation. Inaddition tothesecontributedpapers,therewasakeynoteaddressfromDarylPregibon, invitedpresentationsfromKatharinaMorik,RolfBackhofen,andSunilRao,and aspecial¿datachallenge¿session,whereresearchersdescribedtheirattemptsto analyseachallengingdatasetprovidedbyPaulCohen. Thisacceptancerate enabledustoensureahighqualityconference,whilealsopermittingustop- videgoodcoverageofthevarioustopicssubsumedwithinthegeneralheading ofintelligentdataanalysis. Wewouldliketoexpressourthanksandappreciationtoeveryoneinvolved intheorganizationofthemeetingandtheselectionofthepapers. Itisthe behind-the-scenese?ortswhichensurethesmoothrunningandsuccessofany conference. Wewouldalsoliketoexpressourgratitudetothesponsors:Fundac¿ ¿ao paraaCi¿enciaeaTecnologia,Minist¿eriodaCi¿enciaedaTecnologia,Faculdade deCi¿enciaseTecnologia,UniversidadeNovadeLisboa,Fundäc¿aoCalousteG- benkianandIPEInvestimentoseParticipac¿ ¿oe