2° CONFEST de agosto de Rio de Janeiro Reengineering of the population census the french experience and its lessons for implementing new censuses Jean-Michel Durr Ministry of Education, France Former director of the project for redesign the french census – INSEE

2° CONFEST de agosto de Rio de Janeiro The goals of a census Provide official population (enumeration) : state, regions, municipalities… : –to share public funds on the population basis –Seats at parliament Describe characteristics of population and dwellings : –Sex, age –Employment –Migrations –Place of work, commuters –Households –…. –>>> at any geographical level Sample base for household surveys

2° CONFEST de agosto de Rio de Janeiro The traditional census Main features : –Exhaustiveness –Simultaneity –Every ten years or about Advantages : –Coherence of the data : snapshot of the population and dwellings –Data for any geographical level available –Mobilisation of the population and the teams Drawbacks : –Sample for some variables –Refreshment only every 10 years –Problem of quality due to the importance of the operation and the lack of capitalized experience –Fixed dates : may not fit to the evolution –Risk for boycott –Cost of te operation (inc. intercensal headcounts)

2° CONFEST de agosto de Rio de Janeiro Freshness Refreshment only every 10 years : sufficient in the past, but no more : Increasing demand for more frequent local data : –changes in population are going faster : urbanization, migration, social behaviour... –More and more utilisation at a local scale : decentralization, local area policies

2° CONFEST de agosto de Rio de Janeiro Quality Huge operation, difficult to manage and to ensure quality unsufficiently skilled enumerators problem to capitalize experience allways changes in methodology or definition problem to compare censuses over time : –the example of migration : Population census N+10 - Population census N is supposed to measure the evolution of population : = Births + Deaths + balance of migration but affected by differences of quality ot the two censuses : if the balance of migration is and census N overestimates population of and census N+10 underestimates of , the balance of migration will be estimated to zero.

2° CONFEST de agosto de Rio de Janeiro Fixed date The dates of the censuses may structure the analysis of the evolution and may hide the real process : % people living in periurban areas

2° CONFEST de agosto de Rio de Janeiro The situation in the world Mainly decennial census, –Registers in certain countries, but often problem of quality –Sometimes intercensal headcounts (very costly) Increasing demand : –Rapid changes in population and urbanization –At a local scale : decentralisation, more power to local authorities –Users ask for more frequently refreshed information Concerns about quality and efficiency of the operation A need for finding new ways A lot of projects or studies for new methods of census : –Spain, Germany, Israel : register based census –Netherlands : virtual census based on surveys linked to the register –France, USA, Peru : use of rolling census –Brazil : studies for redesign the census –UK, Mexico : studies (surveys + register) –...

2° CONFEST de agosto de Rio de Janeiro The situation in the world - ECE Method Traditional census 3522 Based on registers 37 Registers + headcount54 Registers + surveys 18 Headcount + rolling census -1 Rolling census -1 Total4443

2° CONFEST de agosto de Rio de Janeiro New methods ? Get free of the dogmas of : –Exhaustiveness : Use sample –Simultaneity : Collect information at different time and combine it And many combinations are available : –Sample/exhaustive surveys –Register/administrative sources –Multi annual combination –…

2° CONFEST de agosto de Rio de Janeiro The situation in the 90’s in France General censuses since 1801, every 5 years until 2nd world war Increasing periods between censuses : 7, 8, 9 years due to budget consideration Insufficient legal basis : periodicity Insee and the municipalities’ function Increasing demand for information : At a local scale : décentralization, more responsibility for municipalities, regions Fresher data No population register Progress in : –Sampling techniques (well-balanced) –Geographic information systems (GIS) >> Reconsider traditional general census using rolling census techniques

2° CONFEST de agosto de Rio de Janeiro Rolling census Principles : –Ideas of Kish (1980, 1990…) –Combination of data collected at different periods –Cumulative survey covering a whole country over a period ot time rather than a particular day : Produces annual and multi-year estimates Produces information for all areas updated every year –Exhaustive enumeration or sample

2° CONFEST de agosto de Rio de Janeiro Another rolling census experience American Community survey : –Implement a national sample of 3 million addresses –Profiles every year for communities of 65,000 or more, beginning in 2004 and each year thereafter –3 to 5 year cumulations for communities of less than 65,000 population –but insufficient sample to replace the decennial headcount

2° CONFEST de agosto de Rio de Janeiro Methodology constraint : –Same budget as for a general census : every year, 1/7 th of the general census budget 5 years cycle : –Produce 3 years old data  sampling : survey 5/7 (70%) of population over 5 years

2° CONFEST de agosto de Rio de Janeiro France numbers almost communes under inhabitants (almost 30 millions inhabitants). These communes Have been spread into 5 groups WHEN ? WHO ? HOW ? HOW MUCH ? Each year, in january and february, to avoid problems of seasonal effect One group enumerated each year, More than communes Survey on every inhabitant of the communes of the group. In 2004, every inhabitants in the communes of first group, In 2005, every inhabitants in the communes of second group, etc. Over 5 years, every inhabitant of the communes under inhabitants is enumerated Communes under inhab.

2° CONFEST de agosto de Rio de Janeiro A year for every commune In 2009, we go on … (exemple of Bas-Rhin) "communes 2006" (less than inhabitants) Haguenau Strasbourg Sélestat Saverne

2° CONFEST de agosto de Rio de Janeiro France numbers almost 900 communes over inhabitants : near 30 millions inhabitants WHEN ? WHO ? HOW ? HOW MUCH ? Every commune every year Survey on a 8 % of the dwellings sample each year Over 5 years, 40 % of the population is surveyed Communes over inhab. Each year, in january and february, to avoid problems of seasonal effect

2° CONFEST de agosto de Rio de Janeiro A group of buildings sampled every year In 2009, we go on …

2° CONFEST de agosto de Rio de Janeiro Estratos equilibrados < habitantes ( comunas/30 milhões hab.)  habitantes (900 comunas/30 milhões hab.) Comunas < hab. – Seleção de 20% das comunas por ano – Enumeração exaustiva nas comunas selecionadas – Todos os endereços visitados em 5 anos Comunas >= hab. – Todas as comunas visitadas anualmente – Visita a 8% dos endereços de cada comuna/ano – Serão visitados 40% dos endereços em 5 anos  Estratos adicionais : domicílios coletivos (internatos, instituições etc)- 20% visitados a cada ano Plano amostral : resumo

2° CONFEST de agosto de Rio de Janeiro The new census will produce every year : De jure population for every commune and administrative district : enables to take more frequently in account changes in population –> more equity Detailed statistical results : –At every geographical level (micro data file for tabulation) –Combining data collected during the 5 last years –Relevant for the medium year (Y-2) Overall estimations at national and regional level : based on data collected the last year

2° CONFEST de agosto de Rio de Janeiro Cumulating information Group 1Group 2Group 3Group 4Group 5Group 1*Group 2*Group 3* * Including updates Year of collection 5

2° CONFEST de agosto de Rio de Janeiro How to estimate population of communes < inhab. in Y-2 ? Y-5Y-4Y-3Y-2Y-1Y I II III IV V

2° CONFEST de agosto de Rio de Janeiro Communes > inh. 8% sample every year Mobile sum of the data collected 5 latest years Weighted according to the Y-2 RIL (number of dwellings)

2° CONFEST de agosto de Rio de Janeiro Why Y-2 ? Medium year of the set of data At most 2 years between observation and estimation Mobile average in large communes … But it is possible to estimate Y with the same set of data collected over Y-4 Y

2° CONFEST de agosto de Rio de Janeiro Agenda 1995 : first report 1998 : beginning of the project 2004 : beginning of the new census 2005 : 1st overall estimations (France-regions) : some criteria : Overall estimations (France- regions) : all criteria End of 2008 : first de jure populations 2009 : « cruising speed » dissemination

2° CONFEST de agosto de Rio de Janeiro Utilisation of the new rolling census data General census : a snapshot every 10 years New census : not a movie, rather a slideshow –communes < inhab. : more frequent full enumeration –communes > inhab. : sample survey, but annual update : Suburban districts evolution : for example, changes in the social characteristics local decisions no more dependent on the date of the census Any level : annual update

2° CONFEST de agosto de Rio de Janeiro Rolling samples : two approaches –Things are not changing too much during the period : as if you take a picture with a long exposure time. A certain fuzziness is acceptable If the period is long, for example 5 years, you may consider you estimate the middle year to consider a shorter period (2 years) between observation and estimation –Things may change over the period : you may collect relevant information for each period and combination gives a stronger estimate for an average mobile mean. Otherwise, possible use of small area method (with complementary sources or not)

2° CONFEST de agosto de Rio de Janeiro Flow data : example of migration For example, estimate migration over 5 years : –At country, state, region level, the annual sample is relevant enough : compare population between the present year and 5 years before to calculate the balance of migration. Less problems of quality differences to compare use the question « Where did you live 5 years ago » to build the matrix of flows (region x region) –For small communes, enumerated every 5 years : compare population of the year to population 5 years ago to calculate the balance of migration matrix of flows over 5 years : –the former place of residence of immigrants has been collected at the last survey –the new place of residence for internal emigrants has been collected over the last 5 years in the other communes

2° CONFEST de agosto de Rio de Janeiro Example : commuters Urban area of Montpellier : inhab surveyed every year

2° CONFEST de agosto de Rio de Janeiro How to take benefit of that experience for implementing new censuses Not a unique model : When get free of the two dogmas of exhaustivity and simultaneity, a lot of frameworks are possible : –Sample/not (e.g. : spread the whole population over 10 years) –Level of sampling : commune, building, dwelling… –Use of administrative data/not –Data collection over year/one moment in the year Example : french and american experiences are very different but based on the same principles So : necessary to find the best way according to the national context

2° CONFEST de agosto de Rio de Janeiro Thank you for attention Any questions ?