Censos e “Big Data”: fontes concorrentes ou complementares?

bigdata

Marden Campos, OLAC

A grande novidade dos estudos demográficos nos últimos anos é a utilização de bases de dados virtuais como fonte de informação. Oriundos da internet e do sistema de telefonia –  informações de redes sociais digitais, acesso a sites, chamadas telefônicas, mensagens eletrônicas, servidores de email, dentre outros –, essas grandes bases de dados (“big data”) entraram de vez na lista de fontes que os estudiosos de população lançam mão para estudar o comportamento reprodutivo, o padrão de doenças, a mobilidade espacial, dentre outros aspectos relacionados à dinâmica populacional.  Exemplos disso são a criação de um grupo de trabalho global sobre big data na divisão de estatística das nações unidas , o painel científico da União Internacional para o Estudo Científico de População (IUSSP) sobre Big Data and Population Processes  e a presença de oficinas de trabalho e de uma mesa redonda sobre Web and Social Media for Demographic Research no congresso conjunto da Associação Latinoamericana de População (ALAP) e Associação Brasileira de Estudos Populacionais (ABEP) realizado no último mês de outubro . Além disso, o tema é central para os debates que ocorrem o neste blog , para o qual buscamos contribuir um pouco mais. Sigue leyendo

Os censos e a construção da realidade

 

dna_human

por Marden Campos, OLAC

Uma notícia recente sobre a facilidade de burlar o sistema de cotas raciais para ingresso nas universidades públicas no Brasil* chama nossa atenção quanto a uma faceta pouco discutida do papel das estatísticas de longo alcance na sociedade contemporânea: a influência das pesquisas na construção da realidade social e a entronização dos censos como princípio científico de legitimação de práticas e métodos em áreas e contextos bastante distintos do levantamento estatístico de atributos populacionais.

O sistema de cotas prevê o preenchimento de vagas para alunos de baixa renda, para oriundos de escolas públicas e para indivíduos de cor preta, parda e indígena. Segundo o Ministério da Educação, as vagas reservadas às cotas devem atingir 50% do total de vagas das instituições*.

Longe de querer criticar o sistema de cotas, seus pontos fortes e fracos e as tentativas (ideais ou não) de reverter a histórica discriminação social por que passam os não-brancos e os pobres na sociedade brasileira, o objetivo deste artigo é problematizar a transferência direta da estratégia de levantamento de cor ou raça do Censo Demográfico para outras esferas da realidade. Sigue leyendo

Zika Virus and Demography

 

Izabel Marri and Marden Campos

 

Demographers can barely take part in real world experiments. Normaly, they are left to work with past information and finished events. Surprisingly, the actual frightening association between Zika virus and microcephaly among newborns in Brazil, that has been largely spread by the media¹ ², can, unfortunately, make the opportunity for us to live an exceptional behavior of birth registries and fertility levels estimated for next years.  If the impact of Zika Virus on fertility really exists, we might have a rare opportunity to follow a phenomenon that is nearly impossible or extremely difficult to incorporate into a population projection.

The official population projection for Brazil, launched in 2013, estimates a reduction in birth numbers and fertility levels for the next years, projecting a tendency that has been observed in the last decades for the whole country. The phenomenon is usually explained by two main reasons:  the economic rationale over reproductive behavior or the supremacy of cultural changes that would diminish the number of births. Great regional differences still exists, making less economic developed regions, such as the North and Northeast, and poorest women, the ones susceptible to show greater fertility rates, and where there should be the greatest falls in in the next years.

How can the fear of contracting Zika Virus and having a baby with microcephaly (or other health problem related to the virus) affect the fertility rate of Brazilian women? And how can the illness affect mortality rates among newborns and the number of stillborn?

The time taken until a preventive or curative vaccine is developed or the time it takes until the epidemic is controlled will, probably, influence women’s reproductive behavior. Important to notice is that not every pregnancy is planned in Brazil. Estimates suggest that 46% of births from 2001 e 2006 were not planned (PNDS 2006). Will the epidemic be capable of changing reproductive behavior in order to increase family planning of all women in reproductive ages, or will it be selective to certain ages or socio-economic groups?

If the Zika virus epidemic or the outbreak of microcephaly are rapidly controlled, negative effects over fertility rate can me mild. In contrary, we can observe a recovery of births in the immediate years after the epidemics is over, or even a long lasting transformations on reproductive behavior of Brazilian women.

As Demographers, we will attain to birth registries of next years in order to detect any exceptional decrease, and try to understand what happened (the next round of Demographic and Health Survey is promised for 2017 would be of great value for the task).

An even more difficult task to demographers, however, will be to transform the data and the possible effects of an epidemics into forecasts of fertility rates for Brazil in the short and long run. Projections consider the decline or gain in fertility rates to be constant, printed in monotonic curves, and no space is left for abrupt deviations concentrated in an specific year. The problem can be exacerbated if the oscillations occur at the census year, affecting its results and making forecast more difficult to do.

The epidemics, although abominable, can offer, at least, one opportunity for demographers to understand the consequences of reproductive behavior in fertility data and to improve working methods.

Responding to the Census: should it be mandatory?

Hot topics about Population Census: how to convince people to respond to the interview?

Although the researchers and census users normally do not have much information about the census operations, one of the most challenger points to statistical institutes that carry out the census is how to convince people to respond the interviews. Nowadays, with the advance of demographic transition, this problem is getting more serious, when there is a decrease of the number of people that stay at home to receive the interviewers, as the women are more involved at the job market, couples have few children and there is a high percentage of people living alone.

A recent polemic from Canada revive this issue. Reinstating the 2016 mandatory long form census in Canada may be problematic, as the census has become politicized and participating in the census becoming a statement of one’s political affiliation and not a civic obligation more…

From some national institutes:

Rights groups say Male/Female option insufficient in Census

 

LGBT rights groups are calling on the government to change the questionnaire for the upcoming census because it excludes many people who don’t identify as solely male or female …example (not exclusive) of Canada.

 

 

Directora del INE/Chile: El Censo cada cinco años responde al dinamismo de la población

El Instituto Nacional de Estadística (INE) de Chile anunció que luego de medición de 2017 realizará censos cada cinco años. Siguiendo recomendación de la Cepal, se realizará una medición tradicional cada diez años y una abreviada cada cinco.

La directora del INE Ximena Clark explicó que la instalación de un Censo abreviado cada cinco años responde a indicaciones internacionales que apuntan al dinamismo de la población. Sigue leyendo

International out-migration measures based on information from former residents

An ongoing challenge for demographers is to know the number of international migrants of a country. While the lack of records and the presence of undocumented migrants hinders the numbers of people who come to a country – the in-migrants – at least they are present in the territory, offering possibilities to account for them. On the other hand, provide estimates for those leaving a country – the out-migrants –  is a much more complicated process.

It is argued here the possibilities of use of population censuses to calculate out-migration based on questions about former residents of the country living abroad. It is believed that the population censuses continue to be a major source of information on international migration, especially for the territorial scope of this type of survey. Since migration is usually a rare event, with a high spatial concentration, it is difficult to produce general information based on surveys that not cover the whole territory of a country.

Based on the census, the number of out-migrants can be measured directly or indirectly. The “direct” information are those drawn from the answers given by respondents to the census questions. “Indirect” data are derived from answers to one or more questions of from other data sources and, usually, undergoing demographic modeling to produce estimates. 

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