9[Oct 22]Active learning， experimental design [Daniel Ting].pdf

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1、ActiveLearning,ExperimentalDesignCS294PracticalMachineLearningDanielTingOriginalSlidesbyBarbaraEngelhardtandAlexShyrMotivation•Betterdataisoftenmoreusefulthansimplymoredata(qualityoverquantity)•Datacollectionmaybeexpensive–Costoftimeandmaterialsforanexperiment–Cheapvs.expensi

2、vedata•Rawimagesvs.annotatedimages•WanttocollectbestdataatminimalcostToyExample:1Dclassifier0000011111xxxxxxxxxxUnlabeleddata:labelsareall0thenall1(lefttoright)Classifier(thresholdfunction):h(x)=1ifx>w(0otherwise)wGoal:findtransitionbetween0and1labelsinminimumstepsNaïvemethod

3、:choosepointstolabelatrandomonline•RequiresO(n)trainingdatatofindunderlyingclassifierBettermethod:binarysearchfortransitionbetween0and1•RequiresO(logn)trainingdatatofindunderlyingclassifier•Exponentialreductionintrainingdatasize!Example:collaborativefiltering•Usersusuallyrate

4、onlyafewmovies;ratings“expensive”•Whichmoviesdoyoushowuserstobestextrapolatemoviepreferences?•Alsoknownasquestionnairedesign•Baselinequestionnaires:–Random:mmoviesrandomly–MostPopularMovies:mmostfrequentlyratedmovies•Mostpopularmoviesisnotbetterthanrandomdesign!•Popularmovies

5、ratedhighlybyallusers;donotdiscriminatetastes[Yuetal.2006]Example:Sequencinggenomes•Whatgenomeshouldbesequencednext?•Criteriaforselection?•Optimalspeciestodetectphenomenaofinterest[McAuliffeetal.,2004]Example:Improvingcellcultureconditions•Growcellcultureinbioreactor–Concentr

6、ationsofvariousthings•Glucose,Lactate,Ammonia,Asparagine,etc.–Temperature,etc.•Task:Findoptimalgrowingconditionsforacellculture•Optimal:Performasfewtimeconsumingexperimentsaspossibletofindtheoptimalconditions.Topicsfortoday•Introduction:Informationtheory•Activelearning–Queryb

7、ycommittee–Uncertaintysampling–Information-basedlossfunctions•Optimalexperimentaldesign–A-optimaldesign–D-optimaldesign–E-optimaldesign•Non-linearoptimalexperimentaldesign–Sequentialexperimentaldesign–Bayesianexperimentaldesign–Maximinexperimentaldesign•SummaryTopicsfortoday•

8、Introduction:Informationtheory•Activelearning–Querybycommittee–Uncer