STRATEGICREVIEWOFPANELANDCOHORTSTUDIESLongview面板和队列研究的战略审查朗维尤

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STRATEGICREVIEWOFPANELANDCOHORTSTUDIES

REPORTTOTHERESEARCHRESOURCESBOARDOFTHEECONOMICANDSOCIALRESEARCHCOUNCIL

JeanMartin,UniversityofOxford

JohnBynner,Longview

GrahamKalton,Westat(USA)

PaulBoyle,StAndrewsUniversity

HarveyGoldstein,UniversityofBristol

VernonGayle,StirlingUniversity

SamanthaParsons,InstituteofEducation

AndreaPiesse,Westat

31January2006

Teamassembledby

“Longview”

90MansfieldRoad

LondonNW32HX

STRATEGICREVIEWOFPANELANDCOHORTSTUDIES

CONTENTS

TOC\o"1-3"\h\z

EXECUTIVESUMMARY

4

1 BackgroundandMethod

4

2 Caseforinvestment

4

3 Longitudinalresearchdesign

5

4 HouseholdPanelStudies:BHPS

7

6 Strategy

9

7 DataQuality,MethodologyandAnalysis

10

8 BuildingNewCapacity

10

9 DataAccessandDisclosureControl

11

10 GovernanceandFunding

11

11 Collaboration

12

1 BackgroundandMethod

14

2 CaseforInvestment

17

Ageingpopulation

18

Long-termeffectsofchildhoodexperience

18

Timingoftransitions

19

Demographicshiftsandmobilities

19

Biotechnologyrevolution

19

Culturaldiversity,inequalityandidentity

20

Immigration

20

Globalisation

20

Recommendations

21

3 LongitudinalResearchDesign

22

Typesofdesign

24

Household/familypanels

24

Birthcohorts

24

Specialpopulationstudies

25

Areastudies

25

Recordlinkagestudies

26

Short-termeconomicpanels

26

Studiesofinstitutions

26

Qualitativestudies

27

Experiments

27

Designdecisions

28

Sampledesignandresponse

28

Topiccoverageanddatacollection

29

Measurementissues

31

Modesofdatacollection.

31

Cross-nationalextension

32

Recommendations

33

4 BritishHouseholdPanelSurvey(BHPS)

35

Table4.4 Averagenumberofeventsperannum

40

Twostudiesorone

41

Topiccoverage

41

Sub-samplestudy

42

Datacollectionfrequency

42

Recommendations

43

5 BritishBirthCohortStudies(NCDS,BCS70,MCS)

44

Newcohortstudyfor2012

46

Bridgingthe30yeargap

47

Futuredirections

50

Recommendations

51

6 Strategy

53

ESRCportfolio

53

Newinvestment

54

Development

58

Institutionaldata

58

Administrativedata

59

Internationalcollaboration

59

Recommendations

60

7 DataQuality,MethodologyandAnalysis

62

Methodsforreducinglossesfromattrition

63

Statisticaladjustmentmethodsforhandlingmissingdata

63

Measurementerrors

65

Methodologicalpanels

66

Documentationanddissemination

66

Recommendations

67

8 BuildingNewCapacity

68

Recommendations

70

9 DataAccessandDisclosureControl

70

Confidentialityanddisclosurerisk

71

Datarelease

73

Recommendations

75

10 GovernanceandFunding

76

Recommendations

79

11 Collaboration

80

Researchfunding

80

Crossstudycollaboration

81

Crossdisciplinarycollaboration

81

Policyresearchandacademicresearch

82

Crossnationalcollaboration

83

Standingconference

84

Conclusion

84

Recommendations

84

EXECUTIVESUMMARY

1 BackgroundandMethod

LongitudinalstudiesareaflagshipcomponentofESRC’ssocialsciencedataresourcesthathaveprovedtheirworthinaddressingkeyscientificquestionsofcentralimportancetoindividualandsocietalwell-beingandhavebeenmajoraidstopolicymakers.Theyaretheonlymeansforstudyingprocessesofindividuallifecoursedevelopmentanddynamics,andforstudyingtheeffectsofearliercharacteristicsonlateroutcomes.ThecapabilityoftheUKlongitudinalstudiestoaddressfuturesocietalchallengesrequiresalongtermstrategyandconstantreviewtoensurethatthedatacollectedwillmeetscientificandpolicyneeds.

Longitudinalstudiesareveryexpensivetodevelop,establish,andmaintain.Theyrequirelong-terminvestmenttoensurethattheycanbeconductedefficientlyandthattheywillprovidethedataneededtoaddressthelongitudinalresearchquestionsofconcern.

Thesuccessofalongitudinalstudydependsonstableleadershipfromacommittedprincipalinvestigator(PI)andateamofhighlyskilledresearchers.

UntilrelativelyrecentlyfundingforlongitudinalstudieswasbeenlargelyadhocandlargelydependentonPIadvocacy.Thereisaneedforsubstantialstablefundingforlongitudinaldataresourcesinthefuture.Thisfundingshouldbegearedtoacomprehensivestrategicplanthathasscopeforcontinuationfundingaswellassupportfornewstudies.

Asabasisforestablishingalong-termstrategicplanforESRC-fundedlongitudinalstudies,areviewteamcomprisingsixmembersknowledgeableaboutlongitudinalstudies—includingtwofromtheUS—wasestablished.Theteamcollectedevidenceby:

correspondence,telephoneandpersonalinterviewswithover70expertsandstakeholdersinEngland,Scotlandandsixothercountries;

atwo-dayconsultativeconferenceattendedby42UKandoverseasexperts;

searchesofwebsitesandothersourcesfordocumentationfromwhichthefeaturesof91longitudinalstudiesmainlyfromtheUK,USA,Canada,Germany,Sweden,AustraliaandNewZealand,wereanalysedandrecorded.

2 Caseforinvestment

Theneedforincreasedinvestmentinlongitudinalstudiesisdrivenbytheidentificationofcriticallyimportantresearchquestionsthatrequiremaintenanceandenhancementoftheexistingstudiesandthedevelopmentofnewstudies.Thereisabroadconsensusbetweenanumberofsources,includingtheESRC’sStrategicPlanandtheemergingNationalDataStrategy,aboutthekeyissuesthatlongitudinaldataareneededtoaddress:

Ageingpopulation

Longtermeffectsofchildhoodexperience

Timingoftransitions–demographicshifts

Demographicshiftsandmobilities

Biotechnologyrevolution

Immigration

Culturaldiversityandinequality

Globalisation

Recommendations

ItisessentialthattheESRCthroughtheNationalDataForumensuresthatnewresearchchallengesdemandinglongitudinaldataarerecognisedintheNationalDataStrategyandthatresourcesaresufficienttosupportthelongitudinaldatathatareneeded.

3 Longitudinalresearchdesign

Thekeyissuesgenerateresearchquestionsthatdemanddifferentkindsoflongitudinalresearchdesignforoptimumanswers.Themaindesigns,whichvaryinusefromonecountrytothenextandsupplythebasisforlongitudinalresearchprogrammes,are:

Household/familypanels

Birthcohorts

Repeated(age)cohorts

Agecohorts

Specialpopulationstudies

(e.g.ethnicminorities,immigrants)

Areastudies(involvingdatacollectionfromindividuals/familiesandthelocalinstitutionsandservicestowhichtheyrelate

Economicshort-termpanels

Recordlinkagestudies

Anumberofkeydecisionsneedtobemadetoimplementthedesigns:

sampledesigndetailsincludingwhetherthereshouldberefreshmenttoincludeimmigrantsand/orover-samplingtoimproveanalysiscapabilityforspecialpopulationsub-groupslikeethnicminorities;

datacollectionfrequencyandmode;

topiccoverage;

enhancementthroughtheadditionofadministrative,environmental,institutional,biomedicalandqualitativedata.

Topiccoveragevariesdependingonwhetherthestudyisgeneralpurpose,topic-based(e.g.health,crime,education)ordiscipline-based(e.g.demography,economics,sociology,politicalscience,psychology).Newdataandmeasurementapproachesthatextendthescopeoflongitudinaldatahavetobeconsidered,includingphysicalenvironmentalmeasures(e.g.airquality)andbiomarkerssuchasobesitymeasures.Administrativedatacanbeavaluableadditionsupplyingadditionalinformationthatreducesrespondentburdenorfillinggapsinthelongitudinalrecord.

Linkingadministrativedatatosamplemembersprovidesavaluablemeansofenhancinglongitudinaldata.However,thequalityofsuchdataneedscarefulappraisal.Theissuesofprotectingrespondentconfidentialityandthelegalandotherrestrictionsonaccesstoothersourcesofdatawillneedtobeaddressed.Theseprotectionsmayresultinsignificantlylimitingaccesstothecombinedsurveyandadministrativedata,butthevalueoftheadministrativedatamakesthislimitationanacceptablepricetopay.

LongitudinalstudiesgainthroughcomparisonwithotherstudiesbothintheUKandinternationally.ConsiderationshouldthereforebegiventocoordinatingU.K.longitudinalstudieswiththoseconductedinothercountriesandinthedifferentterritoriesoftheUK.Comparisonisfacilitatedbyharmonisingkeyvariablesacrossstudies.

Recommendations

Longitudinalresearchdesignsshouldbematchedtotheresearchquestionstheyarebestequippedtoanswer.Inongoingstudiessamplesshouldberefreshedandexpandedanddataenhancedasappropriatetosupplythedataneededtoanswernewquestionsandtomeetnewmethodologicalchallenges.

ESRCshouldensurethatnewdesignsareappraisedandtestedtomeetnewresearchneeds,includinghybridsinvolvingqualitativeandquantitativedata,andexperimentalcombinedwith(survey)approaches,aswellasthetriedandtesteddesigns.

ESRCshouldworkthroughtheUKDataForumtosecuregreateraccesstorelevantadministrativedataforlongitudinalstudiesintheUK.

NewmeasurementsandmeasurementapproachesshouldbepilotedtoextendthescopeoflongitudinaldataincludingphysicalenvironmentalmeasuresandbiomarkerssuchasobesitymeasuresandDNA.

Thepotentialforcross-nationalcomparisonsandcomparisonswithintheterritoriesoftheUKshouldbetakenintoaccountindesigningstudies,byharmonisingkeyvariablesandotherrelevantdesignfeaturesbetweenstudies.

4 HouseholdPanelStudies:BHPS

TheBritishHouseholdPanelStudy(BHPS),establishedin1991withasampleof5,500householdsand12,000individualshasproveditsworthinansweringmanyimportantresearchquestions.Ithasseveralhundredactiveusers.Thelongeritcontinues,thewidertherangeofquestionsitcanaddress;henceinterestinanalysingthedataitproducesislikelytoexpandfurther.However,itscurrentsamplesizeisinadequatetosupportanumberofimportantanalysesinsomekeyareas.Themainlimitationsare:

Sub-groupswithrelativelylowprevalenceinthegeneralpopulation–suchaspeoplewithdisabilities,loneparents,absentfathers,differentminorityethnicgroupsandspecificagecohorts–aretoosmallforrobustinference.

Althoughwave-to-waveresponseratesarecurrentlyhigh,attritionoverthelifeofthepanelhasreducednumbersinthemainpanelandisapotentialsourceofbias.

ImmigrantsintotheUKsincethepanelbeganin1992arenotcoveredingeneral.

Agecohortswithinthepanels,includingthoseformedfrompanelmembers’children,havetobetoobroadlydefinedfortheeffectiveassessmentof‘cohorteffects’.Iftheyarefocusedonsingleagesthedatahavetobeaggregatedovermanyyearsconfoundingthecohorteffectswithperiodeffects

Aggregatinginfrequenteventsthatoccuracrossyearsofthestudy(suchasdivorces)untiladequatenumbersareobtainedsimilarlyrequiresmanyyearsofdata.

Geographicalvariationcanonlybecapturedtoalimitedextent.ThesizesoftheaugmentedsamplesinScotland,WalesandthenewpanelinNorthernIrelandnumbersareinsufficientforwithin-countryfine-grainedanalysis.

Recommendations

TheBHPSwouldbenefitgreatlyfromaverysubstantialexpansioninitssamplesize.Weconsidertheproposedexpansionto40,000householdstobefullyjustified.TheexpansionshouldbeachievedbyaugmentingtheexistingBHPSinsuchawaythatthedatacanbeintegrated.

ThecurrentBHPSpanelshouldbecontinuedalongsidethenewsampleunlessbiasduetoattritionbecomestooseriousaproblem.

AnnualdatacollectionshouldberetainedbutasanexpandedBHPSmovesincreasinglytowardsbecomingamultipurposeframeworkforanumberofmatrix/module-basedstudiestheimplicationsofalongertimeintervalbetweenroundsofdatacollectionshouldbeinvestigated.

Wherefeasibleandappropriate,thenewlargerpanelshoulduseamodularandmatrixapproach,rotatingtopicsatlessfrequentintervalseitherforthewholesampleorforparticularsub-groups.Differentmodesofdatacollectiontoreplacepersonalinterviewsforsomewaves,topics,andrespondentsshouldbeconsideredandevaluated.

5 BirthCohortStudies:1958NCDS,1970BCS70,2000MillenniumCohortStudy

Thebirthcohortstudiesstartingwithawholeweek’sbirthsin1946(NationalHealthandDevelopmentStudy),1958(NationalChildDevelopmentStudy),1970(BCS70)respectivelyandawholeyear’s(sampled)birthsin2000/2001(MillenniumCohortStudy)areaneffectivevehicleforstudyingtheeffectsonthehumanlifecourseofexposuretodifferentbiologicalandenvironmental(socialandphysical)influences.Fromwhatwasinitiallymainlyabiomedicaldevelopmentalperspective,interestinthemhasexpandedtoembraceamuchwiderrangeofscientificprogrammessuchastheeconomicreturnstoeducationand,throughusingthestudiesincombination,theimpactonthelifecourseofsocialchange.

Themainlimitationsofthestudiesare:

inabilitytodealwithshort-termlifecoursedynamicsbecauseoftherelativeinfrequencyofdatacollection,particularlyintheearlyyearsofthe1958and1970studies;

absenceofarea-leveldatabecauseofthespreadoftheoneweek’sbirthsthroughoutthecountryonwhichthefirstthreewerebased;

lackofdatacollectedfromothermembersofthefamilytoteaseouttherelationalaspectoflifecoursedevelopment(‘sharedlives’);

increasingproblemwithattritionandnon-responsereducingnumbersforlongitudinalanalysisandpotentiallybiasingthesample;

the30yeargapbetweenthe1970cohortandtheMillenniumcohortmeaningthatlife-courseprocessesincohortsbornacrosstheperiod1970to2000cannotbeobserved;

noinclusionofimmigrantsafterthecohortmemberspasstheendoftheircompulsoryschoolingatage16.

Recommendations

Thecurrentbirthcohortstudiesshouldbecontinuedandsufficientresourcesmadeavailabletosupportdatacollectionacrossthelifespanatanaverageintervaloffouryearsandtocontinuetheintergenerationalcomponents.Crosscohortcollaborationshouldbefacilitatedandharmonisationofthedatacollectedbetweenthemencouragedtosupportcross-cohortcomparison.

Anewcohortstudyshouldbestartedinaround2012torestorethetwelveyearintervalseries.Itshouldbeprecededbyscopingnewdesignstodeterminewhethertoconcentratedatacollectioninoneyearorspreaditoverseveralyearsandalsowhethertostartallcohortsatbirthorsomeatlaterages.

TopartlyfillthethirtyyeargapintheseriesbetweenBCS70andtheMCS,thereshouldbesupportfordataenhancementandpotentiallydatacollectionafter16yearsofagetheAvonLongitudinalStudyofParentsandChildren(ALSPAC).ThepotentialroleoftheLongitudinalStudyofYoungPeopleinEngland(LSYPE)throughadditionofrelevantadministrativedatabacktobirthalsoneedstobeinvestigated.ThefeasibilityofusingtheScottishSchoolLeaversSurveyinthiswayshouldalsobeinvestigated.

6 Strategy

LongitudinalstudiesinwhichESRCisamajorstakeholderconstituteaportfolioforinvestmentanddevelopmentwithintheNationalDataStrategy.Theportfolioincludesnational,area-based,populationsub-group-specificandintergenerationalstudiescoveringarangeofscientificdisciplinesandstudyareas:social,psychological,economic,political,demographic,environmental,bio-medical.Itensurescoverageofthekeyresearchissueswithoutunnecessaryduplicationandestablishesharmonisationofdatabetweenthelongitudinalstudiesasappropriate.

TheprimepurposeoftheESRC-supportedstudiesshouldberecognisedasscientificandtheirintegrityshouldnotbecompromisedtomeetpolicyevaluationrequirements.Whilethestudiesshouldnotbepolicydriven,theyshouldbepolicyrelevant,supplyingtheevidencebaseonwhichpolicycandraw.

TheBHPSandthecohortstudiescannotaddressallmajorlongitudinalresearchquestions,inpartbecauseofsamplesizelimitationsandinpartbecauseoftherangeofdatatheycancollect.Toaddresstheselimitations,largersamplesandalsoother,morespecialised,longitudinalstudiesareneededintheESRCportfolio.

Recommendations

AnationalframeworkshouldbeestablishedundertheauspicesoftheUKNationalDataForumtoprovideanintegratedportfoliooflongitudinalstudiesforarangeofresearchpurposesinwhichESRCisamajorstakeholder.Widespreadinputtotheframeworkfromscientificinterestsacrossthesocialsciencedisciplinesshouldbefacilitated.

TheESRCshouldestablishtaskforcestoundertakedetailedworkonthedesignofanenhancedBHPSandanewbirthcohortstudywithcoordinationbetweenthemtoensurethatthetwotypesofstudycomplementoneanotherintermsofacoherentscientificprogramme.Theyshoulddrawonthewidestpossiblerangeofexpertsubjectmatterandmethodologicaladvice,bothintheUKandinternationally.

Thepotentialforaddingorlinkingadditionaldatatoexistingandnewstudiesshouldbefullyexplored,includingadministrative,biomedical(includingDNA),environmentalandotherdatasubjecttoconstraintsoffeasibilityandquality.

7 DataQuality,MethodologyandAnalysis

Methodologicaldevelopmentiscrucialtodataqualityandthereforetomaximisingthereturnstoinvestmentinlongitudinaldata.Longitudinaldataaresubjecttoerrorsandbiasesthataccumulateovertimeandneedtobetakenintoaccountbydataproducers,analystsandmethodologists.Attentionneedstobedirectedparticularlyatthemajormethodologicalchallengesofattrition,missingdataandmeasurementerrorandoptimumwaysformeetingthem.

Recommendations

Sufficientfundingshouldbeprovidedtoenablelongitudinalstudyteamstoemploysurveymethodsthatwillgeneratethehighlevelofdataqualityneededforlongitudinalanalysisandalsotoconductmethodologicalstudiestoassessdataqualityandtoimprovetheirmethods.

AcknowledgingthesubstantialpastandpresentESRCmethodologicalinitiativessuchasALCDandthecurrentResearchMethodsProgrammeandNationalResearchMethodsCentre,moreshouldbedonetoensurethattheknowledgegainedistransferreddirectlyintoimprovedpractice.

Aswellasfundingfordatacollection,thestudyteamsshouldbeprovidedwithsufficientfundingforpost-fielddatapreparation,statisticaladjustment,documentationanditsdissemination,andpreliminarydataanalysis.

8 BuildingNewCapacity

CapacityintheUKtodesignlongitudinalresearchandanalyselongitudinaldataisinadequateandneedstobedevelopedatanumberoflevels.Becauseofthespecialisednatureoflongitudinalresearch,capacitybuildingneedscannotbemetfullythroughgeneralpurposemethodstrainingprogrammes.Avarietyofprovisionisneededwithinacoordinatednationalprogramme.

Recommendations

Toensurethatlongitudinalstudiesusestateoftheartmethodsandthatthefullanalyticpotentialoflongitudinaldataisrealised,ESRCshouldprovidesubstantialfundingtoexpandandenhancecapacitytoundertakelongitudinalresearch,buildingonitscurrentprogrammes.

Advancedtraininginlongitudinalmethodsshouldbetargetedatanalysts,dataproducers,methodologists,andotherconstituencieswithapotentialinterestinlongitudinalresearch.Anappreciationofthepotentialoflongitudinaldataandbasicanalytictechniquesisneededfromundergraduatelevelupwards.

Fundingforthemainstudiesshouldallowforthedevelopmentofhighlevelstatisticalandsurveyexpertisetohelpintrainingandtheprovisionofadvice.

9 DataAccessandDisclosureControl

Detailedconsiderationofthecomplextopicofdataaccessanddisclosurecontrolisbeyondthescopeofthisreviewsothereportstopslargelyattheendorsementofkeyprinciplesconcerningconfidentialityissuesanddatasensitivityandtheoptionsforaddressingthemwhilemaximisingdataaccess.

Recommendations

Tocapitaliseontheinvestmentinalongitudinalstudy,theESRCshouldseekarrangementsthatallowforthewidestexploitationofthedatabysocialscientists,includingthoseworkingoverseas,whilesafeguardingthedataprovidedbyindividualrespondents.Licensingarrangementsandsafesettingsappearlikelytoprovidethebestmeansofprotectingtheinterestsofrespondentsinrelationtodisclosureofdisclosiveand/orsensitivedatawhilesupportingmaximumresearchuse.

Thefeasibilityofestablishingasmallnetworkofcentresthatprovidesupportandasafesettingfortheanalysisofarangeoflongitudinaldatashouldbeinvestigated.Suchcentrescouldalsoprovidefacilitiesforcross-sectionalstudies.

Tofacilitateinternationalcollaboration,thefeasibilityshouldbeinvestigatedof:

extendinglicensestooverseascollaboratorsthrough‘visiting’status;

licensingsafesettingsforusingUKlongitudinaldataoversease.g.inthesecureenclavesestablishedforanalysingdatacollectedbynationalstatisticalagencies.

10 GovernanceandFunding

Governanceisconcernedwithprotectingthescientificintegrityofstudieswhileensuringaccountability.Fundingconcernstheinfrastructurethatwillensurethestudies’continuation.Mechanismsareneededthatwillprovidethemosteffectivesupport.Tomaintaintheintegrityofthescientificprogrammethatlongitudinaldataserves,theindependenceoftheresearchteamfromfundersinmakingdecisionsaboutdesignandcoveragemustbepreserved.

Recommendations

ESRCshouldensurethatthemajorlongitudinalstudiesarefundedonalonger-termbasisthanoneortwowavesatatimeinordertoprovidestabilityandenablelongtermplanning.Itshouldnegotiateandmanageanyco-fundingarrangements,whichshouldbewelcomedprovidedthattherearenoconsequencesfortheintegrityofthestudy.

ESRCshouldensurethatallresearchfundersandresearchconstituencieswithacurrentorpotentialstakeinlongitudinaldatahavetheirinterestsrepresentedinthedevelopmentofbothalongtermstrategyandfundingarrangementsforlongitudinalstudies.

ESRCshouldexaminethecaseforalongitudinalstudiesfoundationasachannelforfunding.

ESRCshouldensurethateachstudyobtainscontinuingoutsideinputthroughsuchmechanismsasasteeringcommitteeonwhichsponsorsarerepresentedandascientificoversightcommitteetorepresentthewiderresearchcommunitythatthestudyserves.

11 Collaboration

Aframeworkforthedevelopmentofthenationalportfoliooflongitudinalresourcesisvaluableinstressingtheinterconnectednessofallthestudiesinansweringcomplementaryscientificquestions.Forsuchaframeworktooperateeffectivelycommitmenttocollaborationacrossallprogrammecomponentsandfacilitationofcollaborativeopportunitiesiscrucial.

Suchopportunitiesexistatanumberofanumberoflevels:

researchfunding

acrossstudies

acrossscientificdisciplines

policyresearchandacademicresearch

internationalprogrammes

Recommendations

ESRCshouldseekmeansofstrengtheningcollaborationwithMRCandtheotherresearchcouncilsthroughtheUKDataForumoverlongitudinalresearchstrategyand,especiallywithMRC,throughtheestablishmentofjointworkinggroupsofmedicalandsocialscienceresearcherswithjointinterests.

TomaintainmaximumreturnfrominvestmentESRCshouldencourageandfacilitatecollaborationoverthedesignanduseoflongitudinaldataineverywaypossibleatalllevels:betweenlongitudinalstudyteams,scientificdisciplines;analysts;academicandpolicyresearcher;UKandoverseasresearchers.

Astandingconferenceonlongitudinalstudiesshouldbeestablishedwithanannualmeetingandspecialistpanelmeetingsinbetweenandwithperiodicextensiontoaninternationalmeeting.

1 BackgroundandMethod

Britainhasinternationallyrenownedlongitudinalstudieswhichprovideawealthofinformationonthelifehistoriesofpeopleastheymovefrombirthintooldage.Longestestablishedarethebirthcohortstudies,startingrespectivelyin1946,1958and1970andmostrecently2000.TheyproduceapictureofgrowingupinBritainandthesubsequentroutesthroughadultlifethatisunparalleled.In1991ESRCinitiatedtheBritishHouseholdPanelSurvey(BHPS)tomaphouseholddynamicsoveranextendedperiod.TogetherthesestudieshavetransformedourunderstandingoflifeinachangingBritain.Complementaryprojects,rangingfromtheAvonLongitudinalStudyofParentsandChildren(ALSPAC)tothecensus-basedLongitudinalStudy(LS),enrichtheseamoflongitudinaldataavailableforresearch.

Fromtheriskofsmokinginpregnancytothetiminganddurationoffamilypovertyspells,longitudinalstudieshavemadeavitalcontributiontounderstandingwhatinfluenceswell-being,withgrowingemphasisontheeffectsofenvironmentalandsocietalchange.Theyserveaslivinghistoriescapturingthewaysthatlivesunfold.Whenextendedacrossthegenerations,longitudinalstudiesgiveunmatchedinsightsintocyclesofdeprivationandachievement,andtheintergenerationaltransferofresources.Theyaretheonlymeansofunravellingthelong-termeffectsofchildhoodexperiencesandthedynamicsofinequality,ageingandhealthinthehumanlifecourse.

ThestrengthsoflongitudinalstudiesarerecognisedbythenumerousgovernmentenquiriesandpolicydevelopmentstowhichtheBritishstudieshavebeenamajorsourceofevidence.Forexample,thePlowdenCommitteeonPrimaryEducation(1967),theWarnockCommitteeonSpecialEducationalNeeds(1978),theFinerCommitteeonOneParentFamilies(1966-1974),theAchesonIndependentEnquiryonHealthInequalities(1998)andtheMoserCommitteeonAdultBasicSkills(1997-1999)alldrewheavilyonlongitudinaldata.SimilarlynumerouspolicyinitiativesfromSureStarttotheChildPovertyinitiativeandPensionsReformhavereliedheavilyoncohortandpanelstudydatatoaidpolicydevelopmentandt