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PubMed1989

The 1990 U.S. census: how good is good enough?

The 1990 US census is likely to be the most accurate in the nation's history, but it may miss 2 or 3 million people, most of them poor and many of them black or Hispanic. Because the population census is the basis for political apportionment and determines the allocation of a growing share of federal funds to localities and public programs, undercoverage is of great concern to cities, states, and the groups most affected. The statistical methods developed to measure the extent of undercounting in the census have become increasingly reliable, but the official census count has never before been adjusted on the basis of these methods. This article describes plans for the 1990 census and examines a growing controversy over adjustment for an undercount.

Americas↗

PubMed1992

An overview of demographic analysis as a method for evaluating census coverage in the United States.

"Since the 1950 U.S. census, demographic methods based on the fundamental balancing equation of demography have played an important role in the evaluation of the census net undercount. Application of this set of methods, called demographic analysis, results in national estimates of the net undercount for age-race-sex groups. Although results of demographic analysis are readily available in Bureau of the Census publications, the procedures used to estimate each of the components of population change are less well-known. In this paper we review the historical foundation of demographic analysis, beginning with Coale's 1950 census evaluation project and concluding with the recent evaluation of the 1990 census. We examine each of the components of the method, how their estimation has changed over time, and how they were estimated for the 1990 census."

Americas↗

PubMed2004

Intentional control of event counting.

Event counting depends on simple, well-learned knowledge but is effortful and error-prone. In 6 experiments, the authors examined event-counting performance, testing a model that suggests that counting is controlled by minimal goal representations coordinated with perceptual events by temporal synchrony. In Experiment 1, they examined self-paced counting with or without delays that disrupted participants' preferred pacing. In subsequent experiments, participants counted computer-paced events occurring at rhythmic or varied intervals, reporting or verifying totals. Several results support the model: Participants counted rhythmic events more accurately, made undetected undercount errors when counting rhythmic events, and made false alarms to undercount or overcount probes presented at different times. These results suggest that intentions that guide fluent counting specify parameters deictically rather than semantically and that error monitoring is implicit.

Decision Making↗

PubMed2006

Accurately assessing elderly fall deaths using hospital discharge and vital statistics data.

Historically, fatal injury monitoring and surveillance have relied on mortality data derived from death certificates (DC). However, problems associated with utilizing DC have been well documented. Recently, access to and utilization of hospital discharge data (HDD) have offered a new and important secondary source of data regarding in-hospital deaths. However, studies have shown that discrepancies between the HDD and the corresponding DC often exist. This discrepancy was especially evident when comparing HDD to the vital statistics data (VSD) for deaths by falls among those aged 65 and over in 19 states. This was a retrospective forensic review of elderly (age 65 and over) fall-associated fatalities (E880-E888) identified from HDD and VSD in Allegheny County, Pennsylvania, between 1997 and 1998. Seventy-seven cases were identified, with the original manner of death listed as natural (34), suicide (1), and accidental (42) on the DC. Following a forensic review of the cases, the manner of the death on the DC should have been changed from natural to accidental in 28% (n = 12) of the cases, representing an undercount in the VSD. Undercounts were due to a failure of clinicians to account for the significance of a fall event that contributed to subsequent pathology and death. In addition, in that 22% (n = 17) of the HDD fall-associated deaths, the fall did not contribute directly or sequentially to the underlying cause of death, thereby representing an overcount in the HDD. Based on these findings we recommend (1) elderly fall surveillance systems should only count HDD E-coded falls that demonstrate a serious traumatic injury which directly or subsequently results in death, (2) all in-hospital fall-associated deaths should be reported to and reviewed by coroner/Medical Examiner offices for determination of the cause and manner of death, and (3) physicians should be better educated in properly completing death certificates.

Accidental Falls↗

PubMed1988

Miscounting suicides.

A review of research on the classification and counting of deaths reveals little hard evidence supporting claims that suicides are seriously underreported in the United States. The literature contains hints that much of what underreporting does occur is counterbalanced by "overcounting" (i.e., erroneous certifications of false suicides). An analysis of detailed cause-of-death mortality data for the United States indicates that the maximum likely undercount possible, using generous assumptions concerning misclassification frequency and leaving aside the issue of overcounts, was about 26% for 1980. The maximum likely net undercount, taking compensating overcounts into account, is estimated to be under 10%.

Accidents↗

PubMed2002

Underestimates of unintentional firearm fatalities: comparing Supplementary Homicide Report data with the National Vital Statistics System.

OBJECTIVE: A growing body of evidence suggests that the nation's vital statistics system undercounts unintentional firearm deaths that are not self inflicted. This issue was examined by comparing how unintentional firearm injuries identified in police Supplementary Homicide Report (SHR) data were coded in the National Vital Statistics System. METHODS: National Vital Statistics System data are based on death certificates and divide firearm fatalities into six subcategories: homicide, suicide, accident, legal intervention, war operations, and undetermined. SHRs are completed by local police departments as part of the FBI's Uniform Crime Reports program. The SHR divides homicides into two categories: "murder and non-negligent manslaughter" (type A) and "negligent manslaughter" (type B). Type B shooting deaths are those that are inflicted by another person and that a police investigation determined were inflicted unintentionally, as in a child killing a playmate after mistaking a gun for a toy. In 1997, the SHR classified 168 shooting victims this way. Using probabilistic matching, 140 of these victims were linked to their death certificate records. RESULTS: Among the 140 linked cases, 75% were recorded on the death certificate as homicides and only 23% as accidents. CONCLUSION: Official data from the National Vital Statistics System almost certainly undercount firearm accidents when the victim is shot by another person.

Adolescent↗

PubMed2003

Hazardous waste site frequency: use of the capture-recapture method.

This investigation used a two-source capture-recapture method (CRM) for determining ascertainment and undercounts of non-national priority listed hazardous waste sites in the states of Arizona, Maine and Pennsylvania. These findings suggest that ascertainment of hazardous waste sites vary greatly, with some more accurate (i.e., Maine) than others (i.e., Pennsylvania). These data suggest that nontraditional manufacturing states (e.g., Maine) have a higher ascertainment rate than traditional manufacturing states (e.g., Pennsylvania). These results indicate that resources for locating hazardous waste sites should be more heavily allotted to industrialized areas. We suggest that the CRM is a convenient, low cost and effective method for determining (1) the accuracy of previous estimates, and (2) the number of sites in a locale with 95% confidence intervals along with an estimate of the undercount. Findings suggest that estimates of hazardous waste sites should use the CRM to determine and improve accuracy.

Arizona↗

PubMed1994

National diabetes programs. Application of capture-recapture to count diabetes?

OBJECTIVE: To evaluate the utility of capture-recapture methods using multiple, routinely collected, computerized data sources to estimate the numbers and prevalence of diabetes. Methods employed for regional and national monitoring of diabetes have been too inaccurate or too expensive. RESEARCH DESIGN AND METHODS: A survey was undertaken that used four sources of ascertainment to identify prevalent cases of known diabetes in community of Northern Italy: diabetic clinic and family physicians, hospital discharges, prescriptions, and reagent strips and insulin syringes. Capture-recapture methods were employed to estimate the number of missing cases and to adjust for undercount to accurately estimate the number of people who had diabetes. RESULTS: We identified 2,069 unique prevalent cases of known diabetes with the intensive case-finding procedure. The diabetic clinic and family physicians data source identified the largest number of cases. The evaluation of the two sample capture-recapture estimates showed that they were all biased downward because of dependencies between sources. Log-linear modeling was employed to take into account the dependence among all data sources and the heterogeneity of diabetic patients. This method estimated that 2,586 cases existed, resulting in an ascertainment-adjusted prevalence of 2.77% (95% confidence interval, 2.44-3.10). Thus, despite the active case identification, approximately 20% could not be identified. However, the number of cases and rates could easily be adjusted using capture-recapture. CONCLUSIONS: The study shows that a two-sample capture-recapture estimate could be very biased if the investigator is not assured that the sources are independent. However, if at least three data sources are employed, log-linear models allow estimation of the number and prevalence rate adjusted for the degree of undercount (in spite of both the dependence of data sources and the heterogeneity of the diabetic population). The critical factor, however, is that the application of multiple sources with capture-recapture methods could be applied across broad geographical areas and across time to have cost-effective monitoring of diabetes at local and national level.

Adolescent↗

PubMedDate not supplied

Uncovering the missing Medicaid cases and assessing their bias for estimates of the uninsured.

General population surveys of health insurance coverage are thought to undercount Medicaid enrollment, which may bias estimates of the uninsured. This article describes the results of an experiment undertaken in conjunction with a general population survey in Minnesota. Responses to health insurance questions by a known sample of public program enrollees are analyzed to determine possible reasons for the undercount and the amount of bias introduced in estimates of uninsured people. While public program enrollees often misreport the type of coverage they have, the impact on estimates of those without insurance is negligible. Restrictions to generalizing the finding beyond this study are discussed.

Bias↗

PubMed1976

Annual fertility rates from Census data on own children: comparisons with vital statistics data for the United States.

This paper begins by describing the procedure and data requirements for calculating annual fertility rates from census data on own children. Then, using data from the United States Censuses of 1960 and 1970, fully adjusted estimates are presented and compared with recorded vital statistics rates. Total fertility estimates derived from own children data for whites average less than two percent lower than the recorded rates- a difference that can be attributed partially to the fact that the estimates are adjusted for net census undercount but the recorded rates are not. Even without adjustments for mortality, children not living with their mothers, and net census undercount, the own children data estimates accurately replicate recorded trends (even though the levels are misspecified). The utility of own children data for the study of differential fertility is discussed.

Adolescent↗

PubMedDate not supplied

A new coincidence model for single particle counters, Part II: Advances and applications.

Accuracy, acceptance limits and methods for U.S.P. (788) contaminating particle assays published in the XXII Revision are refined in U.S.P. XXIII. In both Revisions, although different numerical values and methods are employed, particle contamination limits remain constants for all S.V.I. container volumes. The effect of this quality standard is high particle concentration acceptance limits in the smallest S.V.I. container sizes. The effect of these high concentrations is to introduce both undercount errors and false counts into U.S.P. (788) SVI contaminating particle assays. There is general agreement that the count of high concentrations of particles by a single particle light extinction counter result in an increase of the average size of the distribution of particles reported and a decrease in their total number. The error mechanism is termed "signal coincidence." Understanding and control of both these problems is unified with the introduction of the count efficiency parameter. Part I of this paper makes available two core concepts with which evaluation and control of coincidence error in single particle counters can be accurately quantified. These two core concepts are the "Particle Triggered Poisson Model," a new more accurate statistical model of the particle counting process and a concentration measure that includes the effect of particle size on the counting capability of a detector. Use of these concepts make it possible to evaluate particle detector count efficiency capability from experimental data of the coincidence effect. This is an application paper. It combines the theory in the Part I paper with the replicability of particle counters into a simple test protocol. The test results can be used to calculate a contour of particle size and count within which both undercount errors and the introduction of false counts into U.S.P. (788) particle assays are controlled. From the data analyzed it can be seen that any single particle size test cannot effectively evaluate detector performance. The use of the theory and methodology described can help realize the intent of the U.S.P. (788) SVI particle contamination assay.

Calibration↗

PubMed1981

Falling household size and its effect on metropolitan population growth and density.

"In determining metropolitan population size and changes therein, urban theorists traditionally have focused on the number of occupied dwelling units or households and have assumed that these households are equal in size. This paper argues that average household size is an indicator of how intensively the housing stock is utilized and that there is substantial variation in household size across SMSAs in the U.S. The experience of 150 SMSAs is examined for the time period 1960 to 1970. The study model attributes varying household size to differentials in birth and divorce rates, racial composition and age of housing. Ramifications of recent household size declines involve the internal spatial organization of metropolitan areas and the Census controversy with cities over alleged undercounts of urban populations."

Americas↗

PubMed1995

Consistent correction of data for aboriginal populations.

"A consistent correction procedure is used to determine improved, consistent estimates by sex of census age distributions, intercensal births, intercensal deaths and net migration by age for the Aboriginal populations of the Northern Territory, South Australia and Western Australia during the period 1986-91. Undercount estimates and life tables show the Aboriginal populations to have lower coverage in statistical collections and much higher death risks than the total Australian population. Inter-regional net migration estimates show that component of change can no longer be ignored."

Age Distribution↗

PubMed1999

A methodological strategy for a one-number census in the UK.

"As a result of lessons learnt from the 1991 [U.K.] census, a research programme was set up to seek improvements in census methodology. Underenumeration has been placed top of the agenda in this programme, and every effort is being made to achieve as high a coverage as possible in the 2001 census. In recognition, however, that 100% coverage will never be achieved, the one-number census (ONC) project was established to measure the degree of underenumeration in the 2001 census and, if possible, to adjust fully the outputs from the census for that undercount. A key component of this adjustment process is a census coverage survey (CCS). This paper presents an overview of the ONC project, focusing on the design and analysis methodology for the CCS. It also presents results that allow the reader to evaluate the robustness of this methodology."

Censuses↗

PubMed1993

Using information from demographic analysis in post-enumeration survey estimation.

"Population estimates from the 1990 Post-Enumeration Survey (PES), used to measure decennial census undercount, were obtained from dual system estimates (DSE's) that assumed independence within strata defined by age-race-sex-geography and other variables. We make this independence assumption for females, but develop methods to avoid the independence assumption for males within strata by using national level sex ratios from demographic analysis (DA).... We consider several...alternative DSE's, and use DA results for 1990 to apply them to data from the 1990 U.S. census and PES."

Americas↗

PubMed1993

A three-sample multiple-recapture approach to census population estimation with heterogeneous catchability.

"A central assumption in the standard capture-recapture approach to the estimation of the size of a closed population is the homogeneity of the 'capture' probabilities. In this article we develop an approach that allows for varying susceptibility to capture through individual parameters using a variant of the Rasch model from psychological measurement situations. Our approach requires an additional recapture. In the context of census undercount estimation, this requirement amounts to the use of a second independent sample or alternative data source to be matched with census and Post-Enumeration Survey (PES) data.... We illustrate [our] models and their estimation using data from a 1988 dress-rehearsal study for the 1990 census conducted by the U.S. Bureau of the Census, which explored the use of administrative data as a supplement to the PES. The article includes a discussion of extensions and related models."

Americas↗

PubMed1994

Coverage of the Great Britain census of population and housing.

The extent of the undercount in the 1991 U.K. census and its consequences are described. The author notes that "the 1.2 million non-response, the difference between the published census figure and the final population estimate, is concentrated among young adults aged 20-34 years, particularly males, but includes significant numbers of young children and of very elderly people (80 years old and older)." Ways to reduce the level of non-response in future censuses are discussed.

Censuses↗

PubMed1998

The tragedy of the census.

The author discusses the debate on how to reduce the undercount error in the 2000 U.S. census. He reviews the history of the census, and considers the impact of the "opposing ¿interest groups' represented in Congress and elsewhere debating methodological issues that can affect the distribution of census-allocated resources [who] tend to favor methodological choices that will increase their resources."

Americas↗