surveying homelessness

A recent NYT article, entitled “582,462 and Counting“, is describing how the USA Federal Administation is running a yearly survey of homeless people. By sending agents and volunteers in the streets and shelters to get an idea of the magnitude of the problem. The figure of 582,462 was the one produced by HUD (the US Department of Housing and Urban Development) for 2022. In the methodological instructions related to this survey,  I could not find any mention of an advanced statistical technique such as capture-recapture. Despite a possible call to statistical software

The next step is to enter data from the survey into a computer program, such as SPSS, SAS, Excel, or the CoCs’ HMIS.

And both undercount and overcount are not formally addressed

CoCs must ensure that during the PIT count homeless persons are only counted once. It is critical that the counting methods be coordinated to ensure that there is no double-counting. Therefore, CoCs must also collect sufficient information to be able to deduplicate the PIT count (i.e. ensure that the same homeless person was not counted more than once.

(where CoC stands for Continuum of Care and PiT Point-in-Time). (I remember discussing homeless surveys in the 1990’s with researchers from INED, albeit they had already launched their survey and would thus be unable to “recapture” interviewees.)

democracy suffers when government statistics fail [review of a book review]

This week, rather extraordinarily!, Nature book review was about official statistics, with a review of Julia Lane’s Democratizing our Data. (The democratizing in the title is painful to watch, though!) The reviewer is Beth Simone Noveck, who was deputy chief technology officer under Barack Obama and a major researcher in digital democracy, excusez du peu! (By comparison, Trump’s deputy chief technology officer had a B.A. in politics and no other qualification for the job, but got nonetheless promoted to chief…)

“Lane asserts that the United States is failing to adequately track its population, economy and society. Agencies are stagnating. The census dramatically undercounts people from minority racial groups. There is no complete national list of households. The data are made available two years after the count, making them out of date as the basis for effective policy making.” B.S. Noveck

The debate raised by the book on the ability of official statistics to keep track of people in a timely manner is most interesting. And not limited to the USA, even though it seems to fit in a Hell of its own:

“In the United States, there is no single national statistical agency. The process of gathering and publishing public data is fragmented across multiple departments and agencies, making it difficult to introduce new ideas across the whole enterprise. Each agency is funded by, and accountable to, a different congressional committee. Congress once sued the commerce department for attempting to introduce modern techniques of statistical sampling to shore up a flawed census process that involves counting every person by hand.” B.S. Noveck

This remark brings back to (my) mind the titanesque debates of the 1990s when Republicans attacked sampling techniques and statisticians like Steve Fienberg rose to their defence. (Although others like David Freedman opposed the move, paradoxically mistrusting statistics!) The French official statistic institute, INSEE, has been running sampled census(es) for decades now, without the national representation going up in arms. I am certainly being partial, having been associated with INSEE, its statistics school ENSAE and its research branch CREST since 1982, but it seems to me that the hiring of highly skilled and thoroughly trained civil servants by this institute helps in making the statistics it produces more trustworthy and efficient, including measuring the impact of public policies. (Even though accusations of delay and bias show up regularly.) And in making the institute more prone to adopt new methods, thanks to the rotation of its agents. (B.S. Noveck notices and deplores the absence of reference to foreign agencies in the book.)

“By contrast, the best private-sector companies produce data that are in real time, comprehensive, relevant, accessible and meaningful.”  B.S. Noveck

However, the notion in the review (and the book?) that private companies are necessarily doing better is harder to buy, if an easy jab at a public institution. Indeed, public official statistic institutes are the only one to have access to data covering the entire population, either directly or through other public institutes, like the IRS or social security claims. And trusting the few companies with a similar reach is beyond naïve (even though a company like Amazon has almost an instantaneous and highly local sensor of economic and social conditions!). And at odds for the call of democratizing, as shown by the impact of some of these companies on the US elections.

Estudio nacional epidemiológico de la infección por SARS-CoV2 en España [a proper survey]

[A proper survey on the prevalence of the virus in the Spanish population has been launched, with 36,000 representative households chosen from census bases. Thanks to Victor for pointing out the survey!]

• Se desarrollará en las próximas semanas en colaboración con los servicios de salud de las CCAA.

• La Atención Primaria tendrá un papel relevante en la realización de un estudio que pretende estimar el porcentaje de la población española que ha desarrollado anticuerpos frente al nuevo coronavirus.

• En colaboración con el INE, se han seleccionado más de 36.000 hogares españoles, para que la muestra tenga participantes de todos los grupos de edad y localizaciones geográficas.

27 de abril de 2020.- Hoy comienza el Estudio Nacional Epidemiológico de la infección por SARS-CoV2 en España (ENE-COVID), diseñado por el Ministerio de Sanidad y el Instituto de Salud Carlos III (ISCIII) con la colaboración de las CCAA.

Las CCAA proporcionarán el personal sanitario para la realización del proyecto y serán las encargadas de adecuar la logística del estudio de la forma que se considere más adecuada en cada territorio, garantizando que se cumplen todos los requisitos metodológicos del estudio.

A través de las Consejerías de Sanidad o de los propios centros de salud, se irá citando a los participantes para la obtención de muestras. Las llamadas comenzarán este mismo lunes. “La participación es totalmente voluntaria”, ha destacado el ministro de Sanidad, Salvador Illa, “pero aprovecho para animar a todas las personas que sean contactadas a participar en el estudio. Los resultados serán de enorme utilidad para toda la sociedad española.

Con este estudio, el Ministerio de Sanidad y el ISCIII, dependiente del Ministerio de Ciencia e Innovación, en estrecha colaboración con las Comunidades Autónomas, pretenden estimar el porcentaje de la población española que ha desarrollado anticuerpos frente al nuevo coronavirus SARSCoV-2 (concepto conocido como seroprevalencia). La información obtenida será de enorme relevancia para la toma de decisiones de salud pública en el conjunto del Estado.

El papel de los servicios de Atención Primaria de Salud será especialmente relevante a lo largo de todo el proceso.

“the U.S. census needs a different race question”, does it?

“The stated aim — at least for the last half century — [of the census race question] is to help policy makers and demographers assess whether members of different racial groups have equal access to housing, education, employment and other services, as mandated by law.”

A fairly interesting tribune in Science News on the U.S. census race question and the feature that people often self-identify with a category with “doesn’t always match the box someone else might have checked for them”. The discussion focus on failing to protect discriminated groups because people from said discriminated groups do not identify as members of said discriminated groups. Or, because of a genetic ancestry test like 23andme, people from non-discriminated groups do identify as members of a particular discriminated group, e.g., native American Indians. And while there is a separate question on whether or not the respondant is of Hispanic, Latino or Spanish origin, a third of those answering in the affirmative tick the “other race” box in the census. While the sociologist whose work inspired this article calls for different questions in the census, towards a better reflection of actual discrimination, nowhere is the notion of “race” defined or explicited in this paper. Which may be related to the fact that there is no scientifically accepted such definition, as discussed in this UN report. Except all of us belonging to the Homo sapiens sapiens subspecies and descending from common ancestors in Africa.

I thus wonder at the relevance at keeping such a confusing entry in a census: in several European countries including France, it is actually illegal to collect statistics about the race, ethnicity, religion or ancestry. Given the above confusion in the US census and no clear solution to redress the observed biases, discrimination should be fought on sounder bases…

Steve Fienberg’ obituary in Nature

“Stephen Fienberg was the ultimate public statistician.”

Robin Mejia from CMU published in the 23 Feb issue of Nature an obituary of Steve Fienberg that sums up beautifully Steve’s contributions to science and academia. I like the above quote very much, as indeed Steve was definitely involved in public policies, towards making those more rational and fair. I remember the time he came to Paris-Dauphine to give a seminar and talk on his assessment in a NAS committee on the polygraph (and my surprise at it being used at all in the US and even worse in judiciary issues). Similarly, I remember his involvement in making the US Census based on surveys rather than on an illusory exhaustive coverage of the entire US population. Including a paper in Nature about the importance of surveys. And his massive contributions to preserving privacy in surveys and databases, an issue in which he was a precursor (even though my colleagues at the French Census Bureau did not catch the opportunity when he spent a sabbatical in Paris in 2004). While it is such a sad circumstance that lead to statistics getting a rare entry in Nature, I am glad that Steve can also be remembered that way.