Tuesday, December 04, 2018

What’s Really Wrong with the Census

Guest Blogger

Susan Rose-Ackerman and Lena Riemer

The 2020 Census questionnaire is before the federal courts. Commerce Secretary Wilbur Ross ordered the Bureau of the Census to include a question on citizenship status that is subject to judicial challenge. In the first case to reach the trial stage, the US Southern District Court in New York has completed oral hearings. Its holding is expected to generate appeals, and, indeed, the Supreme Court has already agreed to hear one challenge. The cases are occurring within a tight time frame—the final text of the questionnaire must be settled by early summer. At issue is the claim that the head count will be inaccurate.

The decennial census is one of the Constitution’s few substantive mandates (Art. 1, sec. 2, Clause 3). The count is of “persons”, not adults or citizens or voters. Accuracy is the underlying goal of the census requirement because each state’s representation in the House and in the Electoral Collate depends on the accuracy of the census—as does the distribution of federal funds under many programs.[1] In the twenty-first century accuracy requires modern statistical techniques, including sampling and adequate pre-testing of questions. 

In the service of accuracy, statistical theory and practice have developed massively since 1868 when Section 2 of the Fourteenth Amendment removed the 3/5 weight on slaves in the original text and required a count of “whole persons”. Applying the “original’ understanding of statistics in 1789 or even after the Civil War is inconsistent with the original and present-day goal of an accurate count.
The Census Act accepts the value of sampling and states that the Bureau “shall” use sampling everywhere other than for the purposes of reapportionment.[2] The Supreme Court in 1999 read the statute as disallowing sampling for the census but did not reach the constitutional issue.[3] In 2002 the Court permitted a technique called “hot induction” to estimate missing census data because it did not involve a survey.[4] Thus, the case law suggests that the Supreme Court is not hostile to statistics per se, but has, so far, not reached the constitutional issue. Justice Stevens’ dissent in 1999, however, comes close:

Since it is perfectly clear that the use of sampling will make the census more accurate than an admittedly futile attempt to count every individual by personal inspection, interview, or written interrogatory, the proposed [sampling] method is a legitimate means of making the “actual enumeration” that the Constitution commands.

Sampling techniques are sophisticated and widely used in business, academic, and government applications. The Census Bureau uses statistical sampling to estimate key measures such as the unemployment rate, which has been based on sampling since 1937.[5] Sometimes sampling is a cost-saving measure, but in other contexts it is more accurate than counting one-by-one. Yet, direct counts have a certain intuitive appeal. You point to a small pile of apples and ask your friend how many apples are in the pile. Your friend guesses “eight”. You count the apples and discover that there are actually nine. Clearly, the count is more accurate than your friend’s guess. But the superiority of a direct count evaporates as the number counted increases and if the subjects have minds of their own. People are not apples. If you take a census of human beings, their personal characteristics may affect their answers and their willingness to participate. Some may refuse to participate. This refusal could arise from a concern for personal privacy or from an unwillingness to reveal negative information.

The American Statistical Association, the American Sociological Association, and Population Association of America filed an amicus curiae brief in the New York case.[6] It critiques the rushed way in which the question was added to the census questionnaire, which did not follow accepted professional norms. Those arguments are short-term concerns that the Bureau could correct before the next census in 2030. More important is the accuracy of head counts compared with statistical sampling as ways to gather reliable demographic information. The professional associations claim that the citizenship question is unnecessary because the Bureau’s American Community Survey already provides estimates of citizenship status broken down by geographical areas.

Following the case law, the plaintiffs in the district court case did not argue for anything other than an accurate direct count. Yet, statistical sampling can improve the accuracy of the census—as either a complement to or a substitute for a head count, especially with a citizenship question added. Because an accurate population count is the overriding aim of the census clauses, it is unconstitutional to outlaw sampling as a general matter. The ban on sampling will be especially troublesome if a citizenship question is added. If the federal courts continue to accept the ban, then the Constitution forbids inclusion of a citizenship question in a census that allocates House seats and Electoral College votes to the states because it reduces accuracy. Alternatively, if the question remains, the Census Bureau must rely on sampling to produce an accurate head count in order to fulfill its constitutional mandate to provide accurate population data.

Other countries face similar choices in carrying out a census. In Germany public resistance to providing personal data to the government has posed acute problems. In 1987 there were widespread public protests and boycotts of the census.[7] Lacking a constitutional mandate for periodic counts, successive governments delayed the collection of new data. However, faced with out-of-date information and under pressure from the European Union,[8] the government Statistical Office in 2007 sought to achieve an accurate count while minimizing data gathering from individuals. It proposed to rely on official registration documents that cover about 90% of the population, supplemented with household surveys in jurisdictions where it expected the undercount to be high.[9]
The city-states of Hamburg and Berlin objected to this mixed method because it promised to assign them lower population totals than the previous method, disadvantaging them in the allocation of social welfare funds. They did not challenge the use of statistics per se, but only the particular method employed by the government.[10] The Federal Constitutional Court held in favor of the federal government, deferring to the methodology used by the Statistics Office as representing the best expertise available that also limited interference with the fundamental right to “informational self-determination” [para. 286]. The Court stated that

The current state of statistical science cannot establish a clear superiority of the full census method compared to a register-based survey. [...] In comparison to the full census, the register-based method [...] can be an additional cause for faults; but it also provides for the benefits of a greater accuracy.[11]
The German court held that as long as the experts certified that the government’s techniques promised a count at least as accurate as a head count, the methodology would satisfy the German constitution. It recognized the popular appeal of a direct head count stating that:

the full census, as a traditional way to collect data, has also shaped the ideas of the constituents with regard to the accuracy of the determination of the population. In any case, one cannot demand more from a new mathematical-statistical procedure than what a full census can provide.[12]

Lacking a constitutional text, the German court had the freedom to defer to statistical expertise. However, the US Constitution’s mandate for accuracy implies an even greater concern for an accurate count of the population. The decennial census should produce a count that minimizes errors while recognizing that 100% accuracy is impossible. Given that concession to reality, a statute that outlaws the most accurate methods of counting heads should be judged unconstitutional. The interpretation of the clause should reflect state-of-the-art knowledge. Adding a citizenship question to the questionnaire further supports the use of statistical sampling and surveys to counteract the errors introduced by the addition of this question.

Susan Rose-Ackerman is the Henry R. Luce Professor of Law and Political Science, Emeritus, Yale University; Lena Riemer is a Fox Fellow at Yale University.

[1] A Federal District Court allowed the government to collect other information during the head count. See United States v. Moriarty, 106 F. 886, 891 (S.D.N.Y.1901)
[2] 13 USC §195
[4] Utah v. Evans, 536 U.S. 452 (2002).
[8] The EU-wide Population and Housing Census of 2011 aimed to harmonize census methods within the EU and to gather comparable information: Several EU regulations formed the basis for these censuses were inter alia Regulation (EC) No 763/2008 and Regulation (EC) No 1201/20092. The need for up-t0-date data is addressed in para 3 of the BVerfG opinion.
[9] See paragraph 284 of the BVerfG decision.
[10] The previous inferred method of population estimation (Bevölkerungsfortschreibung) attributed a higher number of people to Berlin and Hamburg. The discrepancy between the previously estimated numbers and the ‘new’ census-based numbers was 3,1% in Berlin and 2,5% in Hamburg, whereas in Rheinland-Pfalz for example, the discrepancy was only 0,2% and nationwide on average at 0.6% (paras. 7, 72). The government argued that the old method resulted in an overcount, “Übererfassung”, in the big cities compared to more accuracy in smaller cities (para. 7). Berlin and Hamburg argued that the challenged provisions did not suffice legal clarity as the procedure for example did not contain mathematical-statistical quality standards. (para.78).
[11] “Eine klare Überlegenheit der Vollerhebung gegenüber einer registergestützten Erhebung ist nach dem gegenwärtigen Stand der statistischen Wissenschaft nicht feststellbar. […] Demgegenüber birgt das registergestützte Verfahren […] zwar zusätzliche Fehlerquellen; es weist aber auch die Genauigkeit erhöhende Vorzüge auf.” (para. 285).
[12] “Es kann davon ausgegangen werden, dass die Vollerhebung als traditionelle Erhebungsweise auch die Vorstellungen des Verfassungsgebers im Hinblick auf die Genauigkeit der Ermittlung der von ihm vorausgesetzten Einwohnerzahlen geprägt hat. Daher kann von einem neuen mathematisch-statistischen Verfahren jedenfalls nicht mehr verlangt werden als von der wesentlich aufwendigeren Vollerhebung.“ (para. 280)

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