IsFreeSchoolMealStatusaValidProxyforSocio-Economic

1、Is Free School Meal Status a Valid Proxy for Socio-Economic Status?Graham Hobbs and Anna VignolesCentre for the Economics of Education(funded by Department for Education and Skills)1Family SES potentially key determinant of pupil attainment FSM proxies family SES in much UK educational research:FSM

2、“gap”school composition effectssocial segregationFSM as a control variableEthnicity “gap”class size effects/school resource effects,school effectsCEE FSM Project2CEE ProjectSES measures are generally missing from administrative data setsProject assesses the biases that may arise from using FSM as a

3、proxy in particular contextsLittle in the way of formal evaluation of FSM, with notable exceptionsDfES Statistics of Education: Trends in Attainment Gaps: 2005Croxford 20003CEE ProjectExamine FSM eligibility criteriaExplore national data on benefits to determine what FSM is actually measuringExplore

4、 these relationships in ALSPAC-NPD merged dataPresent a framework for assessing the validity of proxy variable as a “control variable” in OLS regression models, recognising that the validity of FSM as a proxy for family SES is model-specifiAssess the parameter on FSM when FSM is the “variable of int

5、erest”. 4Merged ALSPAC-NPD dataFSM eligibility rules and claimant dataFSM status and family SES in ALSPAC-NPD dataProxy variable frameworkIllustrative exampleOutline5ALSPAC eligibility: Mother resident in Avon. Expected delivery Apr 1991 to Dec 1992.ALSPAC enrolment: 14,049 live birthsALSPAC data: F

6、amily income, presence of partner, mother & partner employment, mother & partner education, mother & partner social classNPD data: FSM, age, gender, ethnicity, EFL, SEN, & KS2 & KS1 attainment Merged ALSPAC-NPD data6Only 11,131 of 14,049 successfully matched to NPDSlightly non-random sampleOnly 5,92

7、4 of 14,049 responded to all SES variablesItem & wave non-responseStrongly non-random sampleFamily SES observed in pregnancy or aged 4-4. FSM measured aged 9-11. Missing data and timing of data7FSM measure: Eligible & claiming FSMFSM eligibility 2005/6: Eligible & claiming IS or IB-JSA Child Tax Cre

8、dit (but not Working Tax Credit) & income less than 13,480Guarantee element of State Pension CreditSupport under part VI of Immigration & Asylum Act 1999FSM eligibility 2001/2: Eligible & claiming IS or IB-JSAFSM measure and eligibility rules8No-one working more than 24 hours per week, a low income

9、& limited capital assets (benefit unit)92% of dependents of IS & IB-JSA claimants were dependants of IS claimants83% of IS claimants with dependents were single parentsAverage IS payment 106 per week for single parents34% of lone parent claimants received IS for 5 yearsIS/IB-JSA eligibility and clai

10、mant data9Conclusions from eligibility rulesChildren in families claiming either IS or IB-JSA were eligible for FSMMajority of these children were in families with a single parent, aged 25-59, and one or two childrenGiven IS and IB-JSA eligibility rules, all of the children should be in families wit

11、hout a parent in full-time employment, with low incomes and limited capital assets.10Potential reasons for non claimingStigma effectsStigma effects varying by schoolConcerns about diet differing by ethnic/ cultural backgroundStory and Chamberlin 2001/ Croxford 200011FSM status and family SES in ALSP

12、AC 12Ordinal associations between FSM status and family SES13Potential reasons for discrepanciesNon claimingMisreporting of income etc. in ALSPACTiming of data For time-varying family SES variables, the true association between FSM status and family SES is likely to be stronger than reported hereObs

13、erve the family SES variables in pregnancy or between ages 44Observe FSM status between ages 911Sample selection14Structural equation:y = 0 + 1x1 + + KxK + q + vLinear projection:q = 0 + 1x1 + + KxK + 1z + rProxy variable regression:y = (0 + 0) + (1 + 1)x1 + + (K + K)xK + 1z + (r + v)Proxy variable

14、framework15q variables i.e. true SES variablesFamily income Parental education Social classParental employmentOne parent status16Structural equation:Proxy variable framework M linear projections:m=1,MProxy variable regression:17Illustrating FSM as a proxy variable The validity of FSM as a proxy for

15、family SES is model-specificIllustrate with example from a (specific) value-added model of Key Stage 2 attainmentAssessing the validity of FSM when FSM is a control variable18Illustrative example19FindingsIn the context of this specific value-added model of KS2 attainment, FSM is an “imperfect proxy

16、” for family SES variablesEstimates of parameters on some variables are biased as a result of using FSMLarge biases on SEN and, in some subjects, ethnicity (but small number of minority ethnic group children in our estimation sample prevents us from making strong inferences for other studies)20FSM as variable of interestWhat is the parameter on FSM in the proxy variable regression is actually measuring? 21Decomposition of FSM differences in KS2 attainment22FindingsAround half of conditional and unconditional FS