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Titlestata.
commiupdate—EnsurethatmidataareconsistentSyntaxMenuDescriptionRemarksandexamplesAlsoseeSyntaxmiupdateMenuStatistics>MultipleimputationDescriptionmiupdateveriesthatmidataareconsistent.
Ifthedataarenotconsistent,miupdatereportstheinconsistenciesandmakesthenecessarychangestomakethedataconsistent.
miupdatecanchangethesortorderofthedata.
Remarksandexamplesstata.
comRemarksarepresentedunderthefollowingheadings:PurposeofmiupdateWhatmiupdatedoesmiupdateisrunautomaticallyPurposeofmiupdatemiupdateallowsyoutochangethevaluesofexistingvariables,whetherimputed,passive,regular,orunregistered;addorremovemissingvaluesfromimputedvariables(orfromanyvariables);dropvariables;createnewvariables;dropobservations;andduplicateobservations(butnotaddobservationsinotherways).
Youcanmakeanyoralloftheabovechangesandthentype.
miupdateandmiupdatewillhandlemakingwhateveradditionalchangesarerequiredtokeepthedataconsistent.
Forinstance,.
dropifsex==1(75observationsdeleted).
miupdate(375m>0obs.
droppedduetodroppedobs.
inm=0)Inthisexample,wehappentohaveveimputationsandareworkingwithongsepdata.
Wedropped75observationsinm=0,andthatstillleft5*75=375observationstobedroppedinm>0.
12miupdate—EnsurethatmidataareconsistentThemessagesmiupdateproducesvaryaccordingtothestyleofthedatabecausethechangesrequiredtomakethedataconsistentaredeterminedbythestyle.
Hadwebeenworkingwithongdata,wemighthaveseen.
dropifsex==1(450observationsdeleted).
miupdate(systemvariable_mi_idupdatedduetochangeinnumberofobs.
)Withongdatainmemory,whenwedroppedifsex==1,wedroppedall75+5*75=450observations,sonomoreobservationsneededtobedropped;butheremiupdateneededtoupdateoneofitssystemvariablesbecauseofthechangewemade.
Hadwebeenworkingwithmlongdata,wemighthaveseen.
dropifsex==1(90observationsdeleted).
miupdate(systemvariable_mi_idupdatedduetochangeinnumberofobs.
)Thestoryhereisverymuchlikethestoryintheongcase.
Inmlongdata,droppingifsex==1dropsthe75observationsinm=0andalsodropstheincompleteobservationsamongthe75inm=1,m=2,m=5.
Inthisexample,therearethreesuchobservations,soatotalof75+5*3=90weredropped,andbecauseofthechange,miupdateneededtoupdateitssystemvariable.
Hadwebeenusingwidedata,wemighthaveseen.
dropifsex==1(75observationsdeleted).
miupdatemiupdate'ssilenceindicatesthatmiupdatedidnothing,becauseafterdroppingobservationsinwidedata,nothingmoreneedstobedone.
Wecouldhaveskippedtypingmiupdatehere,butdonotthinkthatwaybecausechangingvalues,droppingvariables,creatingnewvariables,droppingobservations,orcreatingnewobservationscanhaveunanticipatedconsequences.
Forinstance,inourdataisvariablefarmincome,anditseemsobviousthatfarmincomeshouldbe0ifthepersondoesnothaveafarm,sowetype.
replacefarmincome=0if!
farm(15realchangesmade)Afterchangingvalues,youshouldtypemiupdateevenifyoudonotsuspectthatitisnecessary.
Hereiswhathappenswhenwedothatwiththesedata:.
miupdate(12m=0obs.
nowmarkedascomplete)Typingmiupdatewasindeednecessary!
Weforgotthatthefarmincomevariablewasimputed,anditturnsoutthatthevariablecontainedmissingin12nonfarmobservations;mineededtodealwiththat.
Runningmiupdateissoimportantthatmiitselfisconstantlyrunningitjustincaseyouforget.
Forinstance,let's"forget"totypemiupdateandthenconvertourdatatowide:.
replacefarmincome=0if!
farm(15realchangesmade).
miconvertwide,clear(12m=0obs.
nowmarkedascomplete)miupdate—Ensurethatmidataareconsistent3Theparentheticalmessagewasproducedbecausemiconvertranmiupdateforus.
Formoreinformationonthis,see[MI]noupdateoption.
WhatmiupdatedoesmiupdatecheckswhetheryouhavechangedN,thenumberofobservationsinm=0,andresetsNifnecessary.
miupdatecheckswhetheryouhavechangedM,thenumberofimputations,andadjuststhedataifnecessary.
miupdatecheckswhetheryouhaveadded,dropped,registered,orunregisteredanyvariablesandtakestheappropriateaction.
miupdatecheckswhetheryouhaveaddedordeletedanyobservations.
Ifyouhave,itthencheckswhetheryoucarriedouttheoperationconsistentlyform=0,m=1,m=M.
Ifyouhavenotcarrieditoutconsistently,miupdatecarriesitoutconsistentlyforyou.
Inthemlong,ong,andongsepstyles,miupdatecheckssystemvariablemiid,whichlinksobservationsacrossm,andreconstructsthevariableifnecessary.
miupdatechecksthatthesystemvariablemimiss,whichmarkstheincompleteob-servations,iscorrectand,ifnot,updatesitandmakesanyotherchangesrequiredbythechange.
miupdateveriesthatthevaluesrecordedinimputedvariablesinm>0areequaltothevaluesinm=0whentheyarenonmissingandupdatesanythatdiffer.
miupdateveriesthatthevaluesrecordedinpassivevariablesinm>0areequaltothevaluesrecordedinm=0'scompleteobservationsandupdatesanythatdiffer.
miupdateveriesthatthevaluesrecordedinregularvariablesinm>0equalthevaluesinm=0andupdatesanythatdiffer.
miupdateaddsanynewvariablesinm=0tom>0.
miupdatedropsanyvariablesfromm>0thatdonotappearinm=0.
miupdateisrunautomaticallyAswementionedbefore,runningmiupdateissoimportantthatmanymicommandssimplyrunitasamatterofcourse.
Thisisdiscussedin[MI]noupdateoption.
Inanutshell,themicommandsthatrunmiupdateautomaticallyhaveanoupdateoption,soyoucanidentifythem,andyoucanspecifytheoptiontoskiprunningtheupdateandsospeedexecution,butonlywiththeadrenalinerushcausedbyasmallamountofdanger.
Whetheryouspecifynoupdateornot,weadviseyoutorunmiupdateperiodicallyandtoalwaysrunmiupdateafterdroppingoraddingvariablesorobservations,orchangingvalues.
Alsosee[MI]intro—Introductiontomi[MI]noupdateoption—Thenoupdateoption