Are Educational Differentials In Mortality Increasing in the United States? Samuel H. Preston and Irma T. Elo. PARC Working Paper Series WPS 95-01

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1 POPULATION AGING RESEARCH CENTER Ar Educational Diffrntials In Mortality Incrasing in th Unitd Stats? Samul H. Prston and Irma T. Elo PARC Working Papr Sris WPS " Th authors acknowldg th support of th National Instituts of Halth - National Institut on Aging, Grant numbr P30 AG12836, B.J. Soldo, P.I." 3718 Locust Walk Philadlphia, PA Tl Fax

2 Population Aging Rsarch Cntr, Univrsity of Pnnsylvania Working Papr Sris No August 1, 1994 Ar Educational Diffrntials in Mortality Incrasing in th Unitd Stats? Samul H. Prston Irma T. Elo Population Studis Cntr Univrsity of Pnnsylvania Philadlphia, PA This rsarch is supportd by grants from th National Institut of Aging, AG and P30 HD W ar gratful to Tim Chny for programming assistanc and t o Andrw Fostr, Charls Hirschman, Paul Sorli, Hrbrt Smith, and Tapani Valkonn for usful commnts.

3 Bcaus of th valu that i ndividuals plac on halth and longvity, lvls of mortality ar among th most cntral indicators of social and conomic wll-bing. Analysts ar concrnd not only with th avrag lvl of mortality but also with its distribution among social groups, which is a fundamnta l indicator of social inquality. Th principal dimnsion on which ths assssmnts ar now mad in th Unitd Stats is ducational attainmnt. Th dcisiv shift from occupational groups, th classic dimnsion usd by th Rgistrar-Gnral of England and Wals, to ducational groups as th basis for assssmn occurrd with th publication of Kitagawa and Hausr's (1973) major study of Amrican mortalit t y diffrntials in Educational a ttainmnt has two main advantags rlativ to occupation and incom, th othr common indicators of social stratification. It is availabl for popl who ar not in th labo r forc; and its valu is lss influncd by halth problms that dvlop in adulthood. Sinc halth problms can lad to both high mortality and low incom, compa risons of dath rats of diffrnt incom groups, for xampl, ar biasd by thir mutual dpndnc on a third variabl, th xtnt of ill halth. For ths rasons, ducational attainmnt has bcom th principal social variabl usd in pidmiology as wll as in dmography (Libratos t al. 1988). Two rcnt and highly publicizd studis (Fldm an t al. 1989; Pappas t al. 1993) hav compard th xtnt of rcnt ducational diffrntial in mortality to thos uncovrd by Kitagawa and Haus r (1973). Both concludd that inqualitis hav widnd sinc 1960 for crtain population sub-groups. Howvr, both data sourcs on which ths studis rlid hav important dficincis. In this papr, w rconsidr trnds in ducational mortality diffrntials using a data st that is bttr suitd to xamining this issu, th National Longitudinal Mortality Survy. W also introduc additional masurs o f inquality in an ffort to prsnt a mor complt pictur of inquality trnds. W apply ths masurs to a broadr rang of ags than usd in ithr of th arlir studis. Finally, w considr th quality of data in th 1960 baslin constructd by Kitagawa and Hausr. 2

4 Data Our stimats of ag-sx-ducation spcific dath rats ar basd on th Nationa l Longitudinal Morta lity Survy (NLMS), a mortality follow-up study fundd and dirctd by th National Hart, Lung, and Blood In stitut. Th NLMS Public Us Sampl, th sourc of our data, is basd on fiv Currnt Population Survys (CPS), conductd btwn Mar ch 1979 and March 1981, and contains 637,324 individual rcords. Individua ls numratd in th CPS wr followd up for a fiv-yar priod by linking 1 th rcords to th National Dath Indx (NDI) for th yars This rcord linkag idntifi d 22,649 daths that had occurrd within a fiv-yar priod following th dat of th CPS intrviw t o mmbrs of th fiv CPS cohorts (for dtails on th linkag procdurs, s Rogot t al., 1986). 2 Th NLMS has svral advantags rlativ to th othr two data sourcs usd to study trnds in ducational diffrncs in mortality. F ldman t al. (1989) usd th National Halth and Nutrition Survy Epidmiologi c Followup Study (NHEFS). Th comparativ disadvantag of this sourc is simply on of siz; only 14,407 prsons wr followd up, about 2% of thos i n th public us fil from NLMS. Its small siz rstrictd th authors' attntion to thos ags (55 and abov) whr daths ar most numrous. W show blow th at th data from this sourc ar consistnt with data from th NLMS, although its standard rrors ar highr. 1 Th NLMS Public Us Data Fil is a subst of th largr NLMS databas consisting of 12 cnsus sampls numbring about 1.3 million prsons in th Unitd Stats. Elvn of th 12 cohorts wr takn from Currn t Population Survys con ductd during th priod from March 1973 through March 1985 with on sampl drawn from th 1980 Cnsus of Popul ation. Sampl individuals wr thn matchd to th National Dath Indx (NDI) bginning in 1979, whn th NDI was stablishd, with plans to continu mortality follow-up through (Rogot t al., 1992b). 2 Th fiv CPS survys wr conduct d in March 1979, April, August and Dcmbr 1980, and March For all sampl mmbrs follow-up in days is includd in th Public Us Data Fil and all individuals who wr not linkd to th NDI, and thus considrd to b aliv at th nd of th follow-up, ar givn a follow-up priod of 1827 days (fiv yars). W should not, howvr, that th March 1981 CPS cohort was followd only through th nd of 1985, or approximatly four yars and nin and a half months. W cannot distinguish which sampl individuals blong to this cohort and must accpt a fiv-yar follow-up p riod for thm as wll (National Instituts of Halth, 1992). In addition, th lack of prfct ascrtainmnt of dath in th NDI rsults in som daths bing missd. Rogot t al. (1992, p.2) suggst that "thr is som ascrtainmnt loss, of prhaps 5%, occurring in th matching procss bcaus of rcording rrors in th fils bing matchd." 3

5 Th scond data sourc, usd by Pappas t al. (1993), i s a combination of two sourcs: daths wr drawn from th 1986 National Mortality Followback Survy (N=13,491) and populations at risk wr drawn from th 1986 National Halth Intrviw Survy (N=30,725). Whil this sourc also has fw obsrvations than NLMS, its principal disadvantag is that charactristics of th dad and th living ar r drawn from two diffrnt sourcs. Earlir invstigators hav rvald larg and systmatic discrpancis btwn charactristics for th sam individuals rportd on dath rcords and cnsus rcords (.g., National Cntr for Halth Statistics, 1968, 1969), raising th possibility of srious biass in dath rats constructd from dual sourc s. A similar follow-back survy in rvald a quit diffrnt pattrn of ducationa l diffrntials from thos applying only two yars arlir in a linkd data fil in which al l charactri stics wr drawn from th sam data sourc (Kitagawa and Hausr 1973:32). In particular, ducational diffrntials wr substantially largr for mals in th follow-back survy than in th linkd data fil. Thus, th conclusions ab out trnds that wr rachd by Pappas t al. (1993) may simply rflct th circumstanc that th two obsr vations usd to stablish trnds wr not comparabl. If thy had usd th comparabl sourcs availabl to thm, th widning of ducational diffrntials for mals that th y dmonstrat would hav bn attnuatd. An additional problm with th Pappas t al. data sourc is that th daths includ thos to prsons living in institutions whil th dnominators do not includ such prsons, forcing th authors to rstric t attntion to prsons blow ag 65 and to mak a somwhat arbitrary adjustmnt for daths in institutions 3 blow that ag. Th NLMS and th NHEFS also xcludd prsons who wr in institutions at th bginning of th follow-up priod (although if thy latr ntrd institutions thy would continu to b 3 In th ag rang 25-64, th authors xcludd daths of prsons in th military and prsons who livd i n institutions for mor than half of th yar (Pappas t al. 1993:104). An othr rcnt study (Rogrs, 1992) also usd th 1986 National Halth Intrviw Survy and th 1986 National Mortality Follow-Back Survy to xamin socioconomic mortality diffrntials in th Unitd Stats. Educat ion was not includd as an xplanatory variabl in this analysis and procdurs diffrnt from thos in Pappas t al. (1993) wr usd to adjust for daths in institutions, xmplifying th problms posd by dual data sourcs. 4

6 followd up); howvr, by th natur of th linkd dsign, prs ons in institutions at baslin wr xcludd from both numrator and dnominator. Bcaus of th partial or complt xclusion of prsons i n institutions, dath rats in all thr sourcs ar blow th national lvl rcordd in vital statistics. Lik th two prvious studis, w also bas our 1960 stimats on th Kitagawa and Hausr study (1973) that matchd dath crtificats rgistrd in May-August, 1960 to th 1960 Cnsus of Population takn on April 1. Altogthr, 340,033 dath crtificats wr includd in th study and sarchd in th 1960 cnsus rcords. Th authors publishd both standardizd mortality ratios, basd on an indirc t adjustmnt for ag, and ag-spcific dath rats by ducational attainmnt. In this papr, w bas our trnd stimats on th ag-ducation spcific dath rats for whit mn and womn prsntd in Kitagawa and Hausr (1973:Tabl 2.8). Th Magnitud of Educational Diffrntials in Mortality from Various Sourcs Confidnc in th rliability of masurd ducational diffrntials in mortality would clarly b incrasd if mult ipl sourcs for th sam priod yildd approximatly th sam pattrn of diffrntials. Unfortunatly, as Prston and Taubman (1994) not, th ducational diffrntials in mortality publishd from NLMS (Rogot t al., 1992) appar to b substantially smallr than thos basd on th NHEFS data usd by Fldman t al. (1989), dspit th fact that th priods to which th rats prtain ar roughl similar. This apparnt inconsistncy crats uncrtainty about th magnitud of rcnt ducationa y l diffrntials. Th inconsistncy is dmonstratd in columns 2 and 3 of Tabl 1. Column 3 prsnts th indx numbrs of mortality diffrntials basd on data publishd in th scond NLMS data book for whit mals and fmals (Rogot t al. 1992: Tabl 6). Th variabl bing indxd is th standardizd mortality ratio 5

7 4 (SMR), dfind as th ratio of actual to xpctd daths. Expctd daths ar drivd by multiplying th numbr of prsons at th start of th follow-up with a givn lvl of ducation in a givn ag-rac-s x group by th ovrall probability of dying during th follow-up priod for th ntir ag-rac-sx group. 5 Expctd daths ar calculatd sparatly for a ch cohort in 5-yar ag groups and thn summd. Column 1 prsnts th whit ag-spcific dath rats basd on th NHEFS from Fldman t al. (1989) and column 2 convrts ths rats to indx numbrs, with th mortality lvl of th highst ducation group assignd 6 a valu of 100. Evidntly, th diffrntials ar substantially largr in th NHEFS than in th NLMS. Howvr, diffrnt indx s ar bing compard and ag is tratd diffrntly in th two columns. Both of ths diffrncs ar x pctd to rduc ducational diffrntials in th NLMS column rlativ to thos in th NHEFS. A crtain proportionat diffrnc in ag-spcific dath rats will always translat 7 into a smallr proportionat diffrnc in proportions dying. And bcaus ducational diffrntials i n 4 To obtain comparabl ducational groupings from th NLMS data book to thos publishd by Fldman t al. (1989) w summd th obsrvd and xpctd daths within th givn ag rang ovr th mor dtail ducational catgoris shown and rcalculatd th SMR. d 5 Th follow-up priod for ach of th cohorts diffrd and rangd from 7 yars to.79 yars, avraging 4.8 yars (Rogot t al. 1992b, Tabl A). 6 Fldman t al. (1989) prsnt ag- and sx-spcific annual dath rats by ducational lvl for whit mals and fmals in thr ag (at dat h) groups basd on data for 2,984 whit mn and 3,414 whit womn who wr agd yars at any tim dur ing th follow-up priod. Dath rats for ag-sx-ducation spcific subgroups wr stimatd by dividing th numbr of daths by prson-yars at risk of dath within ach subgroup. 7 Th proof of this proposition is th following. Dfin µ (a) as th forc of mortality at ag a, i.., th agspcific dath rat in th ag intrval from a to a+da as da 0. Th probability of dying in th discrt ag intrval x to x+n, nq x, is thn n q x x x n p(a)µ(a)da/ p(x), whr p(x) is th probability of surviving to ag x. If µ(a) is multiplid by K at all ags in th intrval x to x+n, thn th nw probability of dying will b n q x x x n p K (a) Kµ(a)da/p(x). Thus, th ratio of th nw probability of dying to th old will b 6

8 mortality gnrally dclin with ag, th fact that ags rfr to th ag at xposur in NHEFS and to ag at th outst of xposur in NLMS will caus a contraction of diffrntials in th lattr rlativ to th formr. Finally, publishd NLMS stimats of ducational diffrntials in mortality ar also affctd by th assumptio ns mad concrning daths that occurrd bfor th stablishmnt of th NDI in 1979 t o mmbrs of th March 1973 and Fbruary CPS sampls. In dvloping th dnominators for NLMS rats, no allowanc was mad for ducational (or othr) diffrntials in mortality bfor 1979 (Rogot t al., 1992, Appndix). Sinc such diffrntials wr likly to b prsnt, th ffct of th assumption is to rduc th siz of stimatd ducational diffrntials aftr In ordr to corrct for ths and othr diff rncs in approachs btwn th two sourcs, w hav ranalyzd th NLMS data, using th public us sampl (which contains a subst of all NLMS data) t o calculat dath rats by ag at dath in cat goris comparabl to thos prsntd in Fldman t al. (1989). 8 Rsults ar shown in columns 4 and 5 of Tabl 1. It is clar from th indx numbrs in column 4 that th siz of ducational diffrntials in mortality bcoms comparabl in NLMS and NHEFS whn simila 9 procdurs ar usd. Th man indx numbr for groups with lss than th highst lvl of schoolin r g n q x n q x K x x n x x n p K (a)µ(a)da p(a)µ(a)da Sinc p(a) < 1 at som or all ags btwn x and x+n, th trm in brackts will b lss than on and th proportionat di ffrnc btwn probabilitis of dying will b lss than K, th proportionat diffrnc in agspcific dath rats. 8 Our stimats of ag-sx-ducation spcific dath rats ar constructd by dividing th numbr of daths within ach ag-sx-ducation subgroup by th prson-yars at risk of dath within ach subgroup, whr ag rfrs to ag at dath, an d ar basd on 64,170 whit mn and 77,394 whit womn who wr agd at th initial intrviw and who thus could contribut ithr daths or xposur or both to th ag intrvals in qustion during th fiv-yar followup priod. Individuals for whom ducation was missing ar xcludd from ou r calculations (N=281). Th st imats prsntd ar basd on unwightd cass; th us of wights dos not altr our conclusions. 9 W hav not ag standardizd th NLMS rats to b comparabl with th stimats prsntd by Fldman t al. (1989) b caus w do not know th ag distribution of th prson-yars livd in th NHEFS. Diffrncs 7

9 across all ag-sx groups in Tabl 1 is 137 for NHEFS. Whn publishd NLMS data ar usd, it is only 123. But whn w impos NH EFS critria on NLMS, th man bcoms 135. Narly all of th disparity btwn th sourcs has bn liminatd. Th actual stimats of th ag-sx spcific dath rats basd on th NHEFS and th NLMS ar not idntical. In 13 out of 20 stimats shown, stimats basd on th NHEFS ar highr than thos basd on th NLMS. Givn th longr follow-up priod for th NHEFS (an avrag of 10 yars) than for th NLMS (5 yars), th NHEFS rsults ar likly to captur mor of th mortality xprinc of th institutionaliz d and thus on would xpct dath rats to b highr basd on th NHEFS than on th NLMS. Th formr data also rfr to a tim priod ( ) that is, on avrag, four yars arlir than th lattr ( ), and sinc adult mortality was dclining during this priod, som of th smal l discrpancy btwn th sourcs is likly to rflct mortality trnds. Nvrthlss, among th 20 ag-sxducation groups shown in Tabl 1, in onl y on cas (mals agd at th lowst ducational lvl) do 10 dath rats from th two sourcs diffr signific antly from on anothr at a 5% lvl of significanc. This is th xtnt of disagrmnt xpctd by chanc alo n. W conclud that vidnc on th xtnt of rcnt ducational diffrntials in mortality from ths two indpndnt sourcs is consistnt and that thy hlp to confirm on anothr's rliability. Such is not th cas whn w considr th dath rats constructd by Pappas t al. (1993). Thy prsnt ag-adjustd dath rats (using th ntir U.S. Population in 1940 as a standard) in 1986 among prsons 25 through 64 yars of ag in slctd ducation groups by ag and sx (Pappas t al. 1993: Tabl 1). In Tabl 2 w hav compard ths rats with thos obtaind from th NLMS; th dath rats basd in ag distribution btwn th two sourcs could lad to minor diffrncs btwn th rats. 10 Statistical tsts to dtrmin whthr dath rats basd on th NHEFS and th NLMS ar statisticall ½ diffrnt from on anothr ar basd on th following formula: (DR nhfs - DR nlms)/[(var nhfs + var nlms)]. y 8

10 11 on th NLMS ar also ag-adjustd (within fiv-yar ag groups) using th sam standard. Estimat s basd on th NLMS show a somwhat lowr gradint in mortality by ducational attainmnt than thos obtaind by Pappas t al. using sparat sourcs for numrators and dnominators. In particular, th NLMS-basd dath rat s ar somwhat lowr for individuals with 0-11 yars of schooling and somwhat highr for th most ducatd group than ar th stimats by Pappas t al.. Th rsult is that th ratio of dath rats in th xtrm ducational catgoris for mals is 2.7:1 in Pappas t al., compard to only 2.0:1 in NLMS. For fmals, th discrpancis ar in th sam dirction but smallr: 1.9:1 in Pappas t al. vs. 1.5:1 in NLMS. T h combination of two sourcs usd by Pappas t al. (1993) appars to hav bias d upwards th stimatd xtnt of ducational inquality in mortality. Masurs Th ratio of dath rats among xtrm groups is a vry crud masur of inquality, sinc it taks no account of dath rats in othr groups nor o f th rlativ siz of th groups. In this sction, w dscrib bttr masurs of inquality. Whn applid to data from th NLMS and from th Kitagawa and Hausr study, thy will b usd to rassss trnds in ducational mortality diffrntials. 1. Slop Indx of Inquality Th Slop Indx of Inquality (SII) is an stimat of how much chang in dath rats is associatd with moving up th ducational laddr (Pr ston, Hains, and Pamuk, 1981). In particular, it is an stimat of how much a bsolut dclin in dath rats occurs from th lowst ducational lvl (th 0th prcntil) to th highst (100th prcntil). To construct th SII, w arrang th ducation groups from th fwst to th most yars of school compltd on a horizontal axis and comput ach ducation group's rang in th cumulativ proportionat distribution of th population from th lowst to th highst lvls o f schooling (tha t is, from 0 to 100 in th prcntil ducation distribution). W thn plot ach group's ag- 11 Ag-sx-ducation spcific dath rats wr obtaind in a mannr similar to that dscribd in footnot 9. 9

11 standardizd dath rat at th mid-point of its rang. For ach sx/ducation group, w comput an agstandardizd dath rats by wighting th ag-sx-ducation spcific dath rats in NLMS by a standard ag distribut ion. To facilitat comparisons with th Kitagawa-Hausr rsults for 1960, w usd th 1960 ag distribution for whit prsons as th standard in th a g intrval Sparat sx-spcific standards ar usd. In th ag intrval 65-74, th sx-ducation spcific dath rats ar not ag-standardizd. 12 W thn obt ain th SII, th rlation btwn th dath rats and location on th cumulativ ducation distribution, by wightd last squars rgrssion, whr wights ar th proportions in ac h ducation catgory. An quation is fittd for both 1960 and , sparatly for mals and fmals. By allowing a particular ducational group to chang its location in th prcntil distribution undr this procdur, th mthod taks account of changs in th ducational distribution ovr tim; a group's dath rat is always "locatd" at its midpoint in th prcntil distribution of ducational groups. To construct th SSI for 1960, w us ag-sx-ducation spcific dath rats publishd in Kitagawa and Hausr (1973, Tabl 2.8). For th ag intrval 25-64, dath rats ar givn by tn-yar ag groups for th following ducational catgoris: lss than 8 yars, 8 yars, high school: 1-3 yars, 4 yars, an collg : 1 yar or mor. For th ag intrval 65-74, dath rats ar givn for th following ducationa d l groups: lss than 8 yars, 8 yars, high school: 1-4 yars, and collg: 1 yar or mor Rlativ Indx of Inquality Th slop indx of inquality masurs th absolut xpctd chang in dath rats in moving from 12 Kitagawa and Hausr (1973) publishd ag-sx-ducation spcific dath rats in tn-yar ag intrvals. 13 To tst whthr our rsults ar snsitiv to th way in which ducation is catgorizd in , w ranalyzd th data with an altrnativ classification of th population by ducational attainmnt in th ag intrval Hr w follow Pappas t al. (1993) who classifid ducational attainmnt in 1986 as follows: 0-11 yars of s chool, 12 yars, collg: 1-3 yars and 4 or mor yars. Rsults wr scarcly altrd: th valu of SSI shown i n Tabl 4 at ags in was highr by.03 for mals and.01 for fmals using thi altrnativ grouping. This slight chang is not larg nough to affct any intrprtations rgarding trnds. s 10

12 th lowst to th highst lvls of schooling. Many masurs of inqualit y ar basd on rlativ, rathr than absolut, diffrncs. Th slop indx of inquality can b convrtd into a rlativ masur by simply dividing its valu by th dath rat for all groups combind. Th rsult, which w will rfr to as th rlativ indx of inquality, is quivalnt to th slop of th log of dath rats whn plottd on th cumulativ ducational distribution scal. It indicats th man proportionat dclin in mortality whn ducational lvls advanc from th lowst to th highst. Confusing th issu of rlativ vrsus absolut masurs is th fact that th ratio of surviva l probabilitis btwn two groups, which is a rlativ rathr than an absolut masur of survival, is a function of th diffrnc btwn thir dath rats, an absolut masur of mortality (Kyfitz, 1968). Thr is no obviousl y bst masur of social class diffrncs in mortality. Hnc, w us svral in this papr. 3. Indx of Dissimilarity Th third masur of inquality that w mpl oy is th Indx of Dissimilarity (ID), which is widly usd in th social scincs as a summary mas ur of th diffrnc btwn two distributions. In this cas, th two dis tributions to b compard ar th distributions of daths and of populations at risk of dying by ducational attainmnt. Th valu of ID is calculatd as th sum of th absolut diffrncs btw n proportions of total daths and of population in ach ducati on group (and dividing by two so that th rang of all possibl valus xtnds from 0 to 1). Its valu can b intrprtd as th minimum proportion o f daths that would hav to b rdistributd in ordr to qualiz th distributions of daths and population, thrby liminating all ducational diffrncs in mortality. An ag-standardizd numbr of daths fo r ach ducation group is obtaind by multiplying th ag-standardizd dath r at for ach ducation catgory by th num br of prsons in that ducational catgory. For a particular sx, th 1960 ag distribution for whits is usd as th standard for vry ducational catgory in both 1960 and Th distribution of 11

13 daths is thn compard with th distribution of th population by ducational attainmnt to yild th valu of ID. ID is a rlativ indx of inquality, sinc its valu would not chang if all dath rats wr multipli d by a scalar. Unlik th Rlativ Indx of Inquality, th valu of ID dos not dpnd on th ordring of dath rats by ducational group. It would hav th sam valu rgardlss of what ducational labls wr attac hd to an obsrvd st of daths rats and populations at risk. A closly rlatd indx of inquality is th Gini cofficint, usually mployd in studis of incom inquality. It is also a rlativ masur that dos not attmpt to prsrv th ordring of ducational groups. W hav also usd th Gini cofficint in this study, but r sults wr so similar to thos for th Indx of Dissimilarity that w will not prsnt thm hr. Rsults Th basic rsults of our analyss ar prsntd in Tabl 3, which shows th valu of ach of our thr masurs for mn and womn agd and in both 1960 and Our rsults ar consistn t with prvious findings that show a widning of ducational diffrntials in mortality for whit mn. In both ag intrvals, ach of th thr masurs indicats that ducational inquality in mortality was gratr in than in Although th data sourc usd by Pappas t al.(1993) appars t o xaggrat th xtnt of rc nt inquality at ags 25-64, th us of mor rliabl data dos not rvrs th dirction of chang that thy dscrib. For whit fmals, howvr, our rsults contradict thos of Pappas t al. Both th absolut and rlativ masurs of inquality at ags suggst that ducational diffrntials in mortality hav narrowd rathr than xpandd for whit womn sinc Although thy us a slightly diffrn t ducational classification than th on usd hr, w hav shown that this diffrnc cannot account for th dispari ty in rsults. Most likly, it is attributabl to biass in thir masurs that rsult from usin g 12

14 diffrnt data sourcs for daths and for populations at risk. 14 For womn agd 65-74, our rsults ar mor mixd. Th absolut masur of inquality dclins, whil both rlativ masurs incras. Bing at th low nd of th ducational distribution in was associatd with a smallr absolut pnalty in dath rats than Such an outcom is possibl only whn ovrall dath rats in 1960, but with a largr rlativ pnalty. hav falln, which is clarly th cas for this group in Tabl 3. Th widning of rlativ inquality has, howvr, bn substantially lss for old r womn than for oldr mn. For both sxs, our rsults at ags provid strong confirmation, using a much largr datast and mor laborat masurs, of th gnral tndncis dscribd by Fldman t al.(1989). By far th largst incras in inquality on any masur btwn 1960 and occurrd for mn agd Thr ar rasons to b cautious about th hug incrass in inquality for mn in this ag group. Th complt absnc of diffrntial s for whit mn agd 65+ in 1960 in th Kitagawa-Hausr study appars quit curious in viw of th many conomic and social advantags njoyd by thos wit bttr ducation: mortality indxs for whit mn 65+ with <8, 8, 9-12, and 13+ yars of schooling ar h 1.02, 1.00,.98, and 1.00 rspctivly (Kitagawa and Hausr, 1973, p. 27). Nonwhit mn and wom n abov ag 64 also fail to xhibit an ducati onal gradint in mortality in Ths rsults ar not radily rconcild with indicators of disability. Disability rats showd sharp diffrntials in b y 14 Two othr factors may hav causd th Pappas rsults to ovrsta t th incras in quality. First, rathr than using th sam ag distribution at both tim points, thy appar ntly usd th 1960 ag distribution to dvlop thir inquality masur in 1960 and th 1986 ag distribution to dvlop thir inquality masur in 1986 (Pappas t al. 1993:104). Sinc ducational d iffrntials in mortality diminish with ag (s txt; Fldman t al. 1989), and th 1986 ag distr ibution of yar olds is much youngr than that in 1960 thanks to swolln baby boo m cohorts agd in 1986, th us of diffrnt ag distributions may hav xaggratd th incras in inquality. Scond, thir 1960 data point for whit womn agd with th lowst ducational attainmnt, 0-4 yars, appars to b a transcription rror. According to Kitagawa and Hausr (1973:12), th mortality ratio for thi s group should hav bn 1.60; on th g raph supplid by Pappas t al. (1993:104), this point is plottd at a lvl of about Sinc th is group is at on xtrm of th ducation distribution, its valu has a larg impact on th indx of inquality. 13

15 15 socioconomic status, as shown in Tabl 4. Diffrntials of roughly 2.5:1 in rstrictd activity days and bd disability days btwn th highst and lowst incom classs mak it sm lss plausibl tha t diffrncs in mortality by ducational at tainmnt would b compltly absnt. As notd abov, a followback survy of dcdnts in showd much largr diffrntials by ducation for mn abov ag 64 than did th Kitagawa-Hausr study, although this sourc is hardly dfinitiv. If a problm x ists with th rliability of Kitagawa/Hausr rsults for oldr mn, it is likly to b a product of a rlativly high non-match rat in thir study. An appropriat cnsus form could b locatd for only 74.7% of th daths (Ibid., p. 187). Whil a small sampl of non-matchd cass was followd up, an ducati onal lvl was rportd for only 72.3% of ths cass (Ibid., ). Furthrmor, wh n ducational lvl was r portd (typically by rlativs of th dcdnt) thy wr likly to b in rror (i.., diffrnt from what was rcordd in th cnsus). Th xtnt of this problm is indicatd by th rsults of using th sam follow-up qustionnair among a sampl of matchd cass: among whit mn agd 65+, yars of s chooling wr th sam in th cnsus and th follow-up for only 128 out of 231 matchd cass, or 55% (Ibid., p. 206). It is impossibl to know whthr imputat ions wr accurat in th Kitagawa/Hausr study, but th high non-match rat raiss th possibility that srious rror could hav crpt in. Th most tlling indication that ducational di ffrntials probably did widn btwn 1960 and th priod for this group is that th amount of coding rror in th 1960 study that would b rquird to avrt a widning is implausibly larg. For xampl, if all of th unmatchd daths among whit mals agd 65+ that wr assignd to "collg 1+" in th Kitagawa-Hausr study wr instad assignd to "0-7 yars of schooling", it would l owr th dath rat of th "collg 1+" group by 17.8% and rais that of th "0-7" group by 3.6% (compild from Kitagawa and Hausr, 1973, p. 203). Th rsulting ratio of dat h 15 No tabulations by ducation ar availabl from th National Halth Survy for this priod. For mals agd 65+, incom diffrntials in mortality wr, as for ducation, small in th Kitagawa-Hausr study; a diffrnc of lss than 14% was rportd btwn th l owst (<$2000) and highst (>=$8000) incom catgoris for whits (Kitagawa and Hausr, 1973, p.18). It should b notd that ducational diffrntials in disability ar much largr than ducational diffrntials in mortality for mor rcnt priods as wll (Prston and Taubman, 1994). 14

16 rats of th two groups would still b wll blow th ratios from th NLMS shown in Tabl 1. Ev assigning all of th unmatchd daths to th 0-7 catgory would rais its dath rat by only 20.4%, no nough to avr t an incras in diffrntials btwn 1960 and W conclud that ducationa n t l diffrntials in mortality among oldr whit mals hav almo st crtainly incrasd, although th magnitud of th incras is uncrtain. Discussion This study confir ms two prvious studis that found ducational diffrntials in mortality to hav incrasd for mals si nc Th data st on which our conclusion is basd appars to provid a mor rliabl ba sis for this claim and to produc mor prcis stimats of th changs. Fldman t al. (1989) hav a usful discussion of th factors that may hav bn rsponsibl for this widning. Thy not that trnds in hart disas mortality ar rsponsibl for most of th chang in inquality from all caus s combind. Among th factors thy considr ar changs in th ducational distribution, which w hav dalt wit h mor dirctly hr and shown not to hav accountd for th trnd; cohort-spcific factors that rflct changing childhood nvironmnts; changs in th distribution of cigartt smoking by ducational group, which clarly dos contribut to th trnd but quantitativly is not of major importanc ; improvmnts in mdical and surgical tratmnt of hart disas that may hav diffusd mor rapidl y among bttr ducatd popl; and th possibility that btt r ducatd popl in 1960 wr actually harmd by th mdical practics to which thy had bttr accss. Thy conclud that rasons for th changs in ducational mortality diffrntials ar not asily xplaind and ar likly to b multifactorial. Pappas t al. (1993) add changs in th incom distribution and in accss to a broad rang of halth car to th list of factors that nd to b considrd. Whatvr st of factors is ultimatl y implicatd, som or all of thm must b highly diffrntiatd by sx. W hav shown that inquality actually dclind among womn agd and was basicall y 15

17 stationary for womn agd Th lattr rsult is consistnt with that of Fldman t al. (1989); th formr rsult contradicts that of Pappas t al. (1 993). W can think of two factors that may hav impingd on womn in a way that diffrntiatd thir inquality trnds from thos of mn. First, th priod witnssd a hug incras in labor forc participation rats among womn. For xampl, th labor forc participation rat of marrid womn agd incrasd from 36.2% in 1960 to 68.1% in (U.S. Cnsus Burau 1990:384). This movmnt of womn into th labor forc providd thm with a sourc of incom that was indpndnt of that of thir husbands. At th sam tim, womn's arnings wr gaining on thos of mn (Goldin, 1990). Ths changs may hav nhancd womn's conomic scurity and rduc d th prvalnc of strss-rlatd, as wll as povrty-rlatd, disass. Howvr, th incras in labor forc participation was actually la rgr for bttr ducatd womn, so that this factor may not hav inducd a contraction in mortality diffrntials unlss th changs wr spcially bnficial for poor r womn. A scond fa ctor that may hav disproportionatly bnfitd womn, spcially poorr womn, is Mdicaid. This program, nactd in 1965, provids havi ly-subsidizd halth car for th poor. Eligibility for Aid to Familis with Dpndnt Childrn (AFDC), a wlfar program for singl-parnt housholds, confrs automatic ligibility for M dicaid. Womn ar mor likly to qualify for AFDC than mn, and in fiscal yar 1983, 69.3% of Mdicaid rcipints qualifid for Mdicaid through AFDC. Th rsult is that, of all Mdica id rcipints that yar (including childrn), 64.1% wr fmal (U.S. Dpartmnt of Halth and Human Srvics, 1987). Howvr, th rol of halth insuranc and halth car accss is calld into qustion by th ag pattrn of changs in halth inqualitis. For both mn and w omn, inquality trnds ovr th priod wr mor advrs for prsons agd 65+ than for youngr prsons. Sinc Mdicar was passd in 1965, all prsons agd 65 + hav bn ntitld to basic halth car at littl, if any, cost. If accss to halth car wr a major factor in mortality diffrntials, on would hav xpctd som contraction i n 16

18 diffrntials abov ag 64 rlativ to changs among youngr prsons. Th Amrican xprinc wit Mdicar rsmbls th British xprinc with th National Halth Srvic. Aftr this Srvic wa h s introducd in 1946, inqualitis in mortal ity widnd (Pamuk 1985). Nvrthlss, both Mdicar and th National Halth Srvic providd univrsal covrag, whras Mdicaid has bn targtd spcifically to th most disadvantagd groups. Its rol in mortality lvls and inqualitis, spcially thos of womn, dsrvs furthr invstigation. Our purpos in th is papr is not to supply an xplanation of th various trnds in inquality but to stablish ths trnds with gratr crtainty. W find that th pictur is far mor mixd than th unrmittingly grim pictur that has rcnt ly bn paintd. Whil inquality in dath rats has clarly risn for mn sinc 1960, it has falln among womn agd and rmaind approximatly stationary fo womn agd For ach sx, inquality trnds ar mor advrs for oldr prsons. Whatv r r xplanations ar ultimatly offrd for ths changs, and whatvr policy infrncs ar drawn, will hav to attnd to th varigatd pattrn that w hav dscribd. 17

19 Tabl 1: Comparison of Educational Diffrntials in Mortality Basd on th NHEFS and th NLMS , Whit Mals and Fmals Mortality Ratio Indx Dath Rats Dath rats pr 1,000 pr 1,000 NLMS Sourc NLMS Public NLMS Public Ag and Fldman t Fldman t Book Us Fil Us Fil Education al al MALES 0-11 yars 17.9 (2.2) (0.02) 12+ yars 11.7 (1.7) (0.01) yars 55.4 (4.7) (0.06) 8 yars 41.8 (4.4) (0.05) 9-12 yars 37.7 (3.4) (0.03) 13+ yars 28.4 (4.2) (0.04) yars 87.3 (7.8) (0.10) 8 yars 74.4 (8.0) (0.09) 9-12 yars 70.8 (7.4) (0.07) 13+ yars 63.2 (9.6) (0.09) FEMALES 0-11 yars 8.4 (1.5) (0.01) 12+ yars 6.0 (1.1) (0.01) yars 26.6 (3.4) (0.04) 8 yars 21.0 (2.9) (0.03) 9-12 yars 18.0 (1.9) (0.02) 13+ yars 14.6 (2.7) (0.03) yars 49.7 (5.7) (0.06) 8 yars 50.4 (5.9) (0.05) 9-12 yars 37.9 (4.1) (0.04) 13+ yars 41.7 (6.4) (0.05) Standard rrors of th stimats ar givn in parnthss. Varianc stimats from th NLMS ar basd on th following formula: mˆ i/a i; whr mˆ i is th stimatd dath rat and A i is th aggrgat xposur tim, undr th assumptions that th dath rat rmains tim invariant during th th obsrvation priod and is shard by all sgmnts of th i stratum (Namboodiri, 1991, p.65). Sourc: Fldman t al. (1989), Tabl 2; adaptd from Rogot t al. (1992), Tabl 6; calculations by th authors from th NLMS public us fil. 18

20 Tabl 2: Ag-Adjustd Dath Rats in and 1986 among Prsons Ag in Slctd Education Groups, Whit Mals and Whit Fmals (Daths pr 1,000) Educational Whit Mals Whit Fmals attainmnt NLMS Pappas t al. NLMS Pappas t al. School 0-11 yars yars Collg 1-3 yars yars Pappas t al. stimats ar ag-adjustd dath rats calculatd from ag-spcific dath rats with th ntir U.S. Population in 1940 usd as th standard, basd on data from th 1986 Mortality Followback Survy and th 1986 National Halth Intrviw Survy. Ag-adjustd dath rats from th NLMS ar calculatd from ag-spcific dath rats by fiv-yar ag groups with th ntir U.S. population in 1940 usd as th standard. Sourc: Pappas t al. (1993), Tabl 1. 19

21 Tabl 3: Educational Inquality in Mortality, Unitd Stats 1960 and Whit Mals and Fmals 1 Ag standardizd Slop Indx SSI/ Indx of Sx & Dath Rat of Inquality Dath rat Dissimilarity Yar (pr 100) (SSI) Mals Yars Fmals Mals Yars Fmals Th Slop Indx of Inquality prsntd hr is multiplid by 100 and shows th avrag dclin in standardizd dath rat as on movs from th lowst to th highst lvls of schooling, that is, from 0 to 1 in th proportionat ducation distribution. Not that th ag-standardizd dath rats in this tabl ar also givn pr

22 Tabl 4: Diffrncs in Disability Rats by Family Incom for Mals Agd 65+, Annual Numbr of Rstrictd Numbr of Bd- Family Activity Days Pr Disability Days Incom Prson Pr Yar Pr Prson Pr Yar ($) $ < $ Sourc: National Cntr for Halth Statistics (1963). 21

23 Rfrncs Fldman, J.J., D.M. Makuc, J.C. Klinman and J. Cornoni-Huntly National trnds in ducational diffrntials in mortality. Amrican Journal of Epidmiology 129(5): Goldin, Claudia Undrstanding th Gndr Gap: An Economic History of Amrican Womn. Nw York, NY: Oxford Univrsity Prss. Kyfitz, N Introduction to th Mathmatics of Population. Rading, MA: Addison-Wsly. Kitagawa, E.M. and P.M. Hausr Diffrntial Mortality in th Unitd Stats: A Study in Socioconomic Epidmiology. Cambridg, MA: Harvard Univrsity Prss. Libratos, P., B.G. Link and J.L. Klsy Th masurmnt of social class in pidmiology. Epidmiologic Rviws 10: Namboodiri, K Dmographic Analysis: A Stochastic Approach. Nw York: Acadmic Prss, Inc. National Cntr for Halth Statistics Family Incom in Rlation to Slctd Halth Charactristics. Vital and Halth Statistics, Sris 10, No.2. Washington, DC: Govrnmnt Printing Offic. National Cntr for Halth Statistics Comparability of Ag on th Dath Crtificat and Matching Cnsus Rcord, Unitd Stats: May-August Vital and Halth Statistics, Sris 2, No. 29. Washington, DC: Govrnmnt Printing Offic. National Cntr for Halth Statistics Comparability of Marital Status, Rac, Nativity, and Country of Origin on th Dath Crtificat and Matching Cnsus Rcord, Unitd Stats: May-August Vital and Halth Statistics, Sris 2, No. 34. Washington, DC: Govrnmnt Printing Offic. National Instituts of Halth National Longitudinal Mortality Study. Public Us Fil Documntation. Pamuk, E Social class inquality in mortality from 1921 to 1972 in England and Wals. Population Studis 39: Pappas, G., S. Qun, W. Haddn and G. Fishr Th incrasing disparity in mortality btwn socioconomic groups in th Unitd Stats, 1960 and Nw England Journal of Mdicin 329(2): Prston, S.H., M.R. Hains and E. Pamuk Effcts of industrialization and urbanization on mortality in dvlopd countris. Procdings, IUSSP Intrnational Population Confrnc, Vol. II, pp , Manila, Philippins. Prston, S.H. and P. Taubman Socioconomic diffrncs in adult mortality and halth status. Pp in Th Dmography of Aging (ditd by L. Martin and S.H. Prston). Washington, DC: National Rsarch Council. Rogrs, R.G Living and dying in th U.S.A.: Sociodmographic dtrminants of dath among blacks and whits. Dmography 29(2): Rogot, E., P. Sorli and N.J. Johnson Probabilistic mthods in matching cnsus sampls to th National Dath Indx. Journal of Chronic Disass 39(9):

24 Rogot, E., P.D. Sorli, N.J. Johnson and C. Schmitt A Mortality Study of 1.3 Million Prsons by Dmographic, Social, and Economic Factors: Follow-up. Scond Data Book. National Instituts of Halth. NIH Publication No Washington, DC: Public Halth Srvic. U.S. Burau of th Cnsus. Statistical Abstract of th Unitd Stats: Govrnmnt Printing Offic: Washington, D.C. U.S. Dpartmnt of Halth and Human Srvics Halth Car Financing. Program Statistics. Mdicar and Mdicaid Data Book, Halth Car Financing Administration. Offic of Rsarch and Dmonstrations. HCFA Pub. No Washington, DC: Govrnmnt Printing Offic. 23