New York population projection by age and sex

Transcription

1 New York populaion projecion by and se Couny Projecions Model descripion Jan K. Vink Program on Applied Demographics Cornell Universiy May, 2009 Program on Applied Demographics Web: hp://pad.human.cornell.edu

2 2008 PAD projecions Model descripion Inroducion This documen describes a projecion model developed by Cornell Program on Applied Demographics. The projecion model consiss ou of wo closely relaed pars: a se of algorihms and he numeric coefficiens feeding he algorihms. The values of he coefficiens differ beween counies, he way he algorihms work wih he coefficiens is no dependen on he locaion. Much effor is pu in calculaing he coefficiens in a way ha is in line wih he way hey are used in he algorihms. This documen describes boh he algorihms and he way he coefficiens were derived. The algorihms formula s are in Appendi A. Appendi B conains a lis of insiuions ha are recognized for possible role in he couny populaion couns in he pas and he fuure. Appendi C describes changes made o he model ha led o differen versions of he projeced couns. The projeced Couny populaion couns are published on he inerne. The URL for his web p is: hp://pad.human.cornell.edu/daa/projec ions.cfm General model overview One of he mos widely projecion mehods is called he Cohor-Componen mehod (see [1]). I ceners on he noion ha he populaion can be spli in se cohors and ha changes in he size of each of he cohors can be spli ino 3 componens: birhs (only he younges cohor), deahs and migraion. The componen mehod akes ha noion and projecs he size for each of hose componens for a period in ime and han calculaes he populaion size a he end of he period, giving he size of he populaion a he beginning and he componen sizes. In a formula his looks like: Pop 2 = Pop 1 + B 1,2 D 1,2 + NM 1,2 Where Pop 1 and Pop 2 are he cohor populaion coun a respecively momen 1 and 2, B 1,2 he number of birhs beween 1 and 2, D 1,2 he number of deahs beween 1 and 2 and NM 1,2 he ne migraion beween 1 and 2. The ne migraion in i self is he size of inmigraion minus he size of oumigraion. The projecion model we developed has he following characerisics: The sar populaion is derived from he 2005 populaion esimaes by he U.S. Census Bureau [2], The populaion is divided by se and 5 year groups, wih 85 2

3 and older being he oldes group, The populaion is projeced in 5 year inervals, ending in 2035, Couny specific coefficiens are esimaed using hisoric daa and are held consan. Changes o hese basic model characerisics can be made if necessary and will lead o publicaion of a new version of he resuls. Appendi C describes a hisory of he versions and he changes made in each version. This model descripion firs describes he sar populaion, ne i briefly eplains he sub models for each of he componens and he way Couny specific coefficiens for hese sub models were esimaed. The formulae for he sub models can be found in Appendi A. Sar populaion Each year he U.S. Census Bureau produces pos-census esimaes [3]. These esimaes play an imporan role in disribuion of regional funds, conrols for surveys, denominaor in several raes and raios (e.g. birh raes, moraliy raes employmen raes), ec. Besides oal populaion, he Census Bureau also esimaes populaion by se and several and race/ehniciy caegories. Wih he release of each new se of esimaes, he old se is revised. We waned o use he newes release of hese se/ esimaes for 2005 as our sar populaion, bu found problems wih he disribuions as esimaed by he Census Bureau. Insead we use he laes populaion by se esimae o esimae hisoric crude migraion raes, bu arrive a he sar populaion by projecing a populaion based on he Census 2000 five year forward o 2005 and hen adjus hese such ha he oals mach he newes 2005 oal populaion esimaes by couny. Feriliy The number of birhs born o women in each cohor is calculaed by muliplying he number of females in ha cohor wih an specific birh rae. These numbers are han added over all cohors and muliplied wih a survival rae o ge a oal number of live birhs. As he number of women in ha group we calculae a mid-poin esimae, ha is he aver beween he number of women in he beginning of he ime inerval and he number of women in he same cohors a he end of he inerval. The specific feriliy raes are esimaed by dividing an annual number of birhs o women from a cerain group by he esimaed number of women in ha group. The annual number of birhs by of he moher is derived from annual deailed daa we ge hrough he New York Sae Deparmen of Healh. 3

4 Rockland 0.6 Tompkins Figure 1: Eamples of specific feriliy raes for 5 year inervals The number of women in he denominaor is derived from Census A se-raio deermines he raio beween baby boys and baby girls. Moraliy One of he firs seps our projecion model akes is projecing he porion of he curren populaion ha survives o he ne momen in ime. Survival probabiliies depend on, se and locaion Erie - Female Erie - Male Wescheser - Female Wescheser - Male Birhs Figure 2: Eamples of specific survival raes The survival raes are esimaed using life ables ha are creaed using deailed vial saisics from he New York Sae Deparmen of Healh (deahs by place of residence and single year of in ) and he Census 2000 esimaes for populaion size in each of he groups. The survival rae a Birh is derived compleely from he NYSDOH vial saisics. In he calculaions of he life able (see e.g. [4] for more deails on calculaions of life ables) one has o make assumpions on he life epecancy in he oldes open group. In our calculaions we used he saewide aver life epecancy of he 85+ group as published by he NYSDOH [5]. We ook ha saewide aver life epecancy for he 85+ group and applied ha o each of he couny specific life ables. The life ables were creaed by single year of and as a las sep abridged o accommodae 5 year groups. Migraion The projeced ne migraion is he resul of a number of projeced flows: People moving ino he area from elsewhere in he Unied Saes People moving in from ouside he US People moving ou of he couny In and ou flows of Special Populaions The oal ne migraion 4

5 Inflow from elsewhere in he US The size of his flow is calculaed by aking a fracion of he assumed US populaion in ha se/ group (ouside of he couny we are projecing) and increase ha number if he projeced Special Populaion in ha se/ group is growing. The fracions are esimaed from special abulaions derived from he 2000 Census quesion: Where did you live 5 years ago? The numbers in hese abulaions were adjused for flucuaions in he Special Populaions beween 1995 and The assumed US populaions are based on U.S. Census Bureau projecions [6]. People moving in from abroad The projeced flows of recen immigrans o each of he counies are calculaed as shares of all projeced recen immigrans o New York Sae. The shares and he oal Sae wide size of he recen immigran flows are calculaed using special abulaions derived from he 2000 Census quesion: Where did you live 5 years ago? People moving ou The flow of people in each se/ group ha leave he Couny in a period is calculaed as a fracion of he survivors ha resided in ha Couny a he beginning of he period. If here is a projeced decrease of he Special Populaion in ha se/ group hen he ouflow is increased. The fracions were esimaed from he same special abulaions as he oher migraion flows. Special Populaions In our Projecion model we defined Special Populaions o accommodae flows in and ou of insiuions ha arac people from mosly ouside he couny and mosly for a limied ime. Eamples are people going in, saying a and leaving Colleges & Universiies, Federal & Sae Prisons, Miliary poss and Sae long erm care hospials. We esimaed all migraion raes and such over he whole populaion, hus including he special populaions. Bu flucuaions in he size of hese special populaions in he pas have an impac on hese raes. We correced he esimaed raes so ha hey reflec a consan level of Special Populaions. The projecion model handles flucuaions in he level of Special Populaions separaely. We limied he Special Populaions o Special Populaions in counies where flucuaions would noiceably impac he overall populaion. Appendi B conains he insiuions we recognized for our projecions. Se and characerisics for hese Special Populaions were derived from he /se characerisics of he areas where hese populaions resided a Census Hisoric populaion couns (1990, 1995, 2000 and 2005) were derived from he annual Group Quarer Repors he Program on Applied Demographics prepares for he Census Bureau. Toal Ne Migraion The previous secions described how each of he flows is deermined. They are all by se and group. Ne flows of migraion are calculaed and conrolled for assumed levels of ne migraion. This conrolling is done wih 5

6 a mehod called plus-minus mehod and is described in [1]. Hisoric levels of Ne Migraion are derived hrough residual mehods. Saring in 1990 we worked wih populaion esimaes for 1995, 2000 and 2005 and by correcing for naural increase and one ime changes in Special Populaions we esimaed hisoric Ne Migraion flows. These hisoric flows are epressed as percens of he populaion a he beginning. The hree 5-year raes were averd o ge he rae we used for he projecions. In our curren model we esimae he hisoric ne migraion rae for he oal populaion bu we conrol he female and he male migraion separaely using he same conrol raes. Deviaions from esimaed hisoric raes Migraion ino Corland Couny The special migraion ables produced by he Census Bureau conain erraic number for he inflows of males ino Corland Couny. We looked for a couny ha migh show a similar migraion paern and found ha he neighboring Osego Couny has a very similar female in migraion paern. We hen assumed he male in migraion paern is similar o ha he Osego male in migraion paern. Rockland Couny A special sudy was underaken by Rockland Couny o come up wih beer esimaes and assumpions using local daa and knowledge. The resuls of his sudy are used in our projecions. References [1] Smih, S.K., Tayman, J., & Swanson, D.A. (2001). Sae and local populaion projecions: Mehodology and analysis. New York: Kluwer Academic/Plenum Publishers. [2] U.S. Census Bureau. Couny populaion esimaes by and se hp:// [3] U.S. Census Bureau. Pos census esimaes hp:// [4] NYSDOH life epecancy hp:// [5] Hinde, A (1998). Demographic Mehods. London: Arnold. [6] U.S. Inerim Projecions by Age, Se, Race, and Hispanic Origin: web sie: hp:// daa able: hp:// 6

7 Appendi A Formula General Pop = Pop -1 + Birhs Deahs + Ne Migraion Feriliy Birhs module: BIRTHS * oal = birhrae FEMALES seraio BIRTHS = * BIRTHS, where: se FEMALES se oal ( seraio + seraio ) = Coefficiens esimaion: male female + 1 ( FEMALES + FEMALES ) seraio male = female 1.05, seraio = 1 C 2000 BIRTHS birhrae =, where FEMALES C BIRTHS + 4* BIRTHS + 4* BIRTHS + 3* BIRTHS BIRTHS C = 12 Moraliy Deahs module: ( 1 surv )* BIRTHS + (1 surv ) POP DEATHS = se, 0 se se, * se, 2001 Coefficiens esimaion: surv DEATHS C 2000 se,0 se, 0 = 1 C 2000 BIRTHS se 7

8 surv se, coefficiens are derived from life ables consruced saring wih q-ype moraliy raes: DEATHS q =, where C 2000 se, se, C 2000 POPse, DEATHS + 4* DEATHS + 4* DEATHS + 3* DEATHS DEATHS C = 12 The life ables were calculaed unabridged and hen abridged o he appropriae groups. Anoher assumpion ha had o go in he life ables and only influences he survival raes for he oldes -group is an assumpion abou he life-epecancy a he open-ended group. The unabridged life able was calculaed in single years upo 84 and had open inerval 85+. The assumpion is ha he life epecancy a ha is equal for all Counies and can be copied from a sae wide able on life-epecanc. Migraion BASE = START = END = INMIGR = size size size , END inmraese inmshare ma, BASE, START, se, NETMIGRATION = nerae * se, = ( size, se, ) se, = ( size * spchar, se, ) , = ( size * spchar, se, ) ( uspop POP + BASE START ) se, * nyimmigraion ( 0, ENDse, BASEse, ) ma( 0, STARTse, 1 BASEse, 1 ) * ( POPse, DEATHS se, + BASEse, STARTse, ) + ( 0, START BASE ) ma( 0, END BASE ) oumrae OUTMIGR = ma se, 1 se, 1 NETMIGRATION = ADJIN * INMIGR ADJOUT * OUTMIGR, wih ADJIN and ADJOUT such ha : * se se, se, + se, se, se, ( POP + BASE START) + ( END BASE) + se, Eample o eplain Special Populaion calculaions: Assume ha inmrae and oumrae were based on an insiuion wih 1500 male and 300 male (oal 1800). Suppose furher ha we projec for a cerain projecion period ha his insiuion has 2100 residens a he beginning of he period and 1950 a he end. We keep he characerisics consan. In his eample we calculae he Special Populaion correcions for male year old a he end of he period. A he beginning of he projecion period his cohor was and is projeced o be 1750 in 8

9 size (1500/1800 * 2100) and in he end 325 (300/1800 * 1950). The 1750 is 250 more han he 1500 in he base and we add hose as era s o he ou-migraion, he 325 is 25 more hen he base and hose 25 are added o he immigraion, so he correced ne migraion is 225 (25-250) lower hen he uncorreced ne migraion. Anoher way o arrive a his oal correcion is: wih consan base couns he ne migraion would be ( ), wih he projeced couns he ne migraion is = -1425, which is indeed 225 lower. Coefficiens esimaion: The coefficiens are esimaed solving he same formula for he coefficiens using daa from a special Census Bureau abulaion o fill in values for he migraion flows. The size of he Special Populaions comes from he annual Group Quarer repor he Program on Applied Demographics prepares for he U.S. Census Bureau. We gaher ha informaion hrough inerviews and overseeing sae ncies. The size of he miliary insallaions is esimaed from he Census couns, where we ook he corresponding CDP as he size of ha insallaion. Characerisics are esimaed using characerisics of he blocks where he insiuions are locaed and where mos of he residens are in ha Group Quarers. There is one insiuion ha was build and occupied since We derived is characerisics from he yearly Profile of Inmae Populaion Under Cusody prepared by he New York sae Deparmen of Correcional Services. 9

10 Appendi B Special Populaions The able underneah liss all he insiuions ha were used o adjus ne migraion raes in case here were flucuaions a ha insiuion. A in he Se/ column indicaes ha ha we esimaed se and characerisics for he residens of ha insiuion and ha deailed immigraion and oumigraion raes are adjused for coun variaions in he pas and in he projeced fuure. Couny Insiuion Se/ Albany College Of Sain Rose Siena College Sae Universiy Of New York-Albany Capiol Disric Psychiaric Cener Allegany Alfred Universiy Houghon College - Houghon Campus Suny Ag Tech College-Alfred Cayuga Auburn Correcional Faciliy Cayuga Correcional Faciliy Chemung Elmira College Elmira Correcional Faciliy Souhpor Correcional Faciliy Clinon Alona Correcional Faciliy Clinon Correcional Faciliy Sae Universiy Of New York-Plasburgh Plasburgh Air Force Base Corland Sae Universiy College-Corland Duchess Bard College Downsae Correcional Faciliy Fishkill Correcional Faciliy Green Haven Correcional Faciliy Maris College Vassar College Harlem Valley Sae Hospial Taconic//Wassaic Developmenal Cener Hudson River Sae Hospial Esse Adirondack Correcional Faciliy Moriah Shock Incarceraion Correcional Faciliy Ray Brook Federal Correcional Insiuion (Ray Brook Fci) 10

11 Franklin Camp Gabriels Franklin Correcional Faciliy Upsae Correcional Faciliy + Bare Hill Correcional Faciliy Sunmoun Developmenal Cener Greene Cosackie Correcional Faciliy Greene Correcional Faciliy Jefferson Cape Vincen Corr Faciliy For Drum Waerown Correcional Faciliy Livingson Groveland Correcional Faciliy For Men + Livingson Corr Faciliy Sae Universiy College-Geneseo Madison Cazenovia College Colgae Universiy Suny Ag Tech College-Morrisville Oneida Hamilon College Insiue Of Technology A Uica/Rome Marcy Correcional Faciliy Mid-Sae Correcional Faciliy Oneida Correcional Faciliy + Mohawk Correcional Faciliy Uica College Mohawk Valley Psych Cener Griffiss Air Force Base Orleans Albion Fem Corr Faciliy Orleans Corr Faciliy Osego Harwick College Sae Universiy College-Oneona S. Lawrence Clarkson College Gouverneur Corr Faciliy Ogdensburg Correcional Faciliy Riverview Corr Faciliy Sain Lawrence Universiy Sae Universiy Of New York-Posdam Suny Ag Tech College-Canon Sain Lawrence Psychiaric Cener Schoharie Suny Ag Tech College-Cobleskill Seneca Willard Drug Treamen Campus Five Poins Correcional Faciliy Willard Sae Hospial 11

12 Suffolk Long Island Developmenal Cener//Suffolk Developmenal Cener Cenral Islip Sae Hospial Pilgrim Psychiaric Cener Kings Park Sae Hospial Tompkins Cornell Universiy Ihaca College Ulser Easern Correcional Faciliy Shawangunk Correcional Faciliy Sae Universiy College-New Palz Ulser Corr Faciliy Wallkill Correcional Faciliy Washingon Grea Meadow Correcional Faciliy Washingon Correcional Faciliy Wyoming Aica Correcional Faciliy Wyoming Correcional Faciliy 12

13 Appendi C Model version hisory Version This is he firs published version and conains he algorihms and coefficiens as described in his documen. Version nn Corland Couny male ou migraion The ou migraion raes for men have uneplained high values. We knew from earlier analysis ha he special migraion abulaions conain an error for Corland couny. The female ou-migraion raes from Corland Couny are very similar o he female raes in neighboring Osego Couny. We copied he male ou-migraion raes from Osego Couny o Corland Couny and used hose for our projecions. Sar populaion The 2005 se/ characerisics as esimaed by he US Census Bureau are no consisen wih he characerisics 5 year earlier in Census As an alernaive sar populaion we projeced he 2005 populaion by using his same projecion model and he Census 2000 populaion as he saring populaion. A raking facor was used o adjus he oals o he Census Bureau s esimaed oals. Version New US Projecions The U.S. Census Bureau published new projecions for he U.S. These projecions are used in he calculaion of migraion ino each of he counies. This version includes he new projecions. Rockland Couny Resuls from a sudy wih Rockland Couny are included in he assumpions. Version Sar Populaion The Census Bureau published new couny esimaes (Vin 2008). This version s crude migraion rae esimaes is based on he Vin 2007 couny populaions by se. The sar populaion oals are adjused o mach he Vin 2008 oals. 13