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PubMed2006

The contribution of Medicaid managed care to the increasing undercount of Medicaid beneficiaries in the Current Population Survey.

BACKGROUND: The Current Population Survey (CPS) is an important source of data for comparing beneficiaries across insurance groups. However, the CPS routinely underestimates the Medicaid population, and for unexplained reasons these underestimates have been increasing over time. OBJECTIVE: We sought to determine whether the penetration of Medicaid managed care is associated with the magnitude of the underestimate of Medicaid beneficiaries in the CPS using a pooled cross-sectional comparison of survey and administrative databases on all California Medicaid beneficiaries younger than 65 years of age. MEASURES: We compared the CPS estimates of Medicaid beneficiaries in California from 1995 to 1999 with the gold-standard number derived from the Medicaid eligibility file for the same time period and examined the association between the CPS underestimate and penetration of managed care in the beneficiary's county. RESULTS: The CPS underestimated the Medicaid population by approximately a third. At the county level, errors in estimated numbers of Medicaid beneficiaries in the CPS increased in association with the penetration of Medicaid managed care. Each percentage point increase in the penetration of managed care was associated with an underestimate in the CPS of 0.4 percentage points. CONCLUSION: A substantial portion of the increase in the underestimates of the number of Medicaid beneficiaries in the CPS can be explained by the growth of Medicaid managed care. Steps must be taken to improve the CPS if this survey is to remain useful for making accurate estimates of Americans' health insurance status.

Cross-Sectional Studies↗
PubMed2001

Undercounts and overstatements: will the IOM report on lesbian health improve research?

In January 1999, the Institute of Medicine (IOM) released a report on lesbian health research that fulfills 3 goals: it provides an extensive review of much of the research that has been done on the health of women who have sex with other women, it addresses the methodological and ethical issues inherent in conducting research on this population, and it suggests avenues for further research. This report will likely help lesbian health researchers gain funding, publish further research in medical journals, and receive support and validation from medical and research institutions. To ensure that such research is useful, benefits the lesbian community, and expands the understanding of lesbian health conditions, particular attention needs to be paid to the methods and definitions used and to the involvement of the lesbian community in designing, implementing, and analyzing the research itself.

Community Health Planning↗
PubMed2005

Widening ethnic mortality disparities in New Zealand 1981-99.

The aim of this paper is to determine the extent of undercounting of Mäori and Pacific deaths in New Zealand during the 1980s and 1990s, and to calculate corrected ethnic mortality and life expectancy trends. We calculated adjustment ratios for undercounting of Mäori and Pacific deaths (and over-counting of non-Mäori non-Pacific (nMnP) deaths) using the linked census-mortality data. These ratios were then used to calculate corrected mortality rates and life expectancies. Mäori deaths were underestimated by a quarter, and Pacific deaths by a third, during the 1980s and early 1990s. Undercounting was minor in the late 1990s following alignment of ethnicity collection on mortality data to approximate the census. Corrected mortality rates demonstrated 30% (males) and 26% (females) decreases among nMnP from 1980-84 to 1996-99, smaller decreases among Mäori (8% and 7%) and no clear change among Pacific people (9% decrease for males, 4% increase for females). The gap in life expectancy increased from an average of 7.7 years in 1980-84 to 10.8 years in 1996-99 for Mäori, and from 3.3 to 7.7 years for Pacific people, in comparison to nMnP people. Deaths among 45-64 and 65 plus year olds, and cardiovascular disease and cancer deaths, were the main contributors to these disparities. The economic reforms in New Zealand during the 1980s and early 1990s impacted harder upon Mäori and Pacific people in terms of unemployment and income, and are a likely explanation for the diverging mortality trends in this period. Both behavioural factors and health services probably also play a role, but in the absence of trend data by ethnicity, their contribution to diverging mortality trends is unknown. Internationally, our study demonstrates marked undercounting of Mäori and Pacific deaths. We strongly encourage researchers and custodians of vital statistics in other countries to investigate the possibility of undercounting of deaths by ethnicity.

Adolescent↗
PubMed1989

Adjusting the 1980 census of population and housing.

"In 1980, several cities and states sued the U.S. Census Bureau to correct census results. This correction would adjust for the differential undercounting of Blacks and Hispanics, especially in cities. In this article, the authors, each of whom testified for New York City and State in their joint lawsuit against the Census Bureau, describe the likely pattern of the undercount and present a method to adjust for it." The authors describe available methods for data adjustment and introduce a regression-based composite method of adjustment, which is used to estimate the undercounts for 66 areas. "As expected, we find that the highest undercount rates are in large cities, and the lowest are in states and state remainders with small percentages of Blacks and Hispanics. Next, we analyze how sensitive our estimates are to changes in data and modeling assumptions. We find that these changes do not affect the estimates very much. Our conclusion is that regardless of whether we use one of the simple methods or the composite method and regardless of how we vary the assumptions of the composite method, an adjustment reliably reduces population shares in states with few minorities and increases the shares of large cities."

Black or African American↗
PubMed1992

How the 1990 Post Enumeration Survey transformed the census adjustment controversy.

The author briefly examines the controversy surrounding the 1980 U.S. census undercount, including a lawsuit entered against the U.S. Bureau of the Census by the City of New York. He then describes the Post Enumeration Survey (PES), introduced after the 1990 census "to measure census coverage (i.e. undercounts) by place and by race and ethnicity, which had not previously been possible.... Results of the 1990 PES show that previous claims about the harmful effects of differential undercounts were exaggerated, but they also [show] that the undercounts and their effects are still there."

Americas↗
PubMedDate not supplied

A new coincidence model for single particle counters, Part I: Theory and experimental verification.

The prerequisites for estimating the effect of signal coincidence on both particle undercounting and the injection of false counts in the implementation of U.S.P. 788 contaminating particle assays by light extinction particle counters are defined. These include a particle concentration measure that varies with particle size and a new model of the counting process. Both prerequisites have been verified empirically: a single normalized equation describes the coincidence effect in all single particle counters. The single parameter of the normalized equation is the number of effective detector volumes per milliliter. A maximum undercount limit of 5% is proposed based on adequately suspended particles. Using the SVP U.S.P. XXII acceptance limits of 10,000 particles per container or the PMA propose 6,000 particles per container maximum for particles > 10 microns in U.S.P. XXIII, undercount errors are estimated for the smallest container sizes. The large concentration of particles below the controlled 10 microns particle size, that has been documented in injectable solutions, can pose an additional 788 measurement hazard. A Poisson model is used to estimate and control the injection of false particle counts into the mandated measurement through particle coincidence. Acceptable counting accuracy limits with present particle counting systems can be achieved by understanding the capabilities of the particle counter measurement system and using a dilution technique when appropriate. The new model of the counting process and the new particle concentration measures can result in standard, conservative, instrument specifications for use in Pharmacopeial contamination testing and in GLP user evaluation tests. Part I of this paper includes the theory of the coincidence effect on particle counting and the particle size distribution measured. A summary of the experimental verification employed to determine coincidence count loss as a function of particle concentration for single particle counters is reported. Part II of this paper describes a practical protocol for the determination of operating limits to achieve a selected coincidence undercount limit for single particle counters.

Drug Contamination↗
PubMed1988

[Modeling matching error and its effect on estimates of census coverage error].

"In this paper, we propose a model for investigating the effect of matching error on the estimators of census undercount and illustrate its use for the 1990 [U.S.] census undercount evaluation program. The mean square error [MSE] of the dual system estimator is derived under the proposed model and the components of MSE arising from matching error are defined and explained. Under the assumed model, the effect of matching error on the MSE of the estimator of census undercount is investigated. Finally, a methodology for employing the model for the optimal design of matching error evaluation studies will be illustrated and the form of the estimators will be given."

Americas↗
PubMed2004

Effects of data limitations when modeling fatal occupational injury rates.

BACKGROUND: Occupational fatal injury rate studies are often based upon uncertain and variable data. The numerator in rate calculations is often obtained from surveillance systems that can understate the true number of deaths. Worker-years, the denominator in many occupational rate calculations, are frequently estimated from sources that exhibit different amounts of variability. METHODS: Effects of these data limitations on analyses of trends in occupational fatal injuries were studied using computer simulation. Fatality counts were generated assuming an undercount. Employment estimates were produced using two different strategies, reflecting either frequent but variable measurements or infrequent, precise estimates with interpolated estimates for intervening years. Poisson regression models were fit to the generated data. A range of empirically motivated fatality rate and employment parameters were studied. RESULTS: Undercounting fatalities resulted in biased estimation of the intercept in the Poisson regression model. Relative bias in the trend estimate was near zero for most situations, but increased when a change in fatality undercounting over time was present. Biases for both the intercept and trend were larger when small employment populations were present. Denominator options resulted in similar rate and trend estimates, except where the interpolated method did not capture true trends in employment. CONCLUSIONS: Data quality issues such as consistency of conditions throughout the study period and the size of population being studied affect the size of the bias in parameter estimation.

Accidents, Occupational↗
PubMed2004

A multiple-record systems estimation method that takes observed and unobserved heterogeneity into account.

We present a model to estimate the size of an unknown population from a number of lists that applies when the assumptions of (a) homogeneity of capture probabilities of individuals and (b) marginal independence of lists are violated. This situation typically occurs in epidemiological studies, where the heterogeneity of individuals is severe and researchers cannot control the independence between sources of ascertainment. We discuss the situation when categorical covariates are available and the interest is not only in the total undercount, but also in the undercount within each stratum resulting from the cross-classification of the covariates. We also present several techniques for determining confidence intervals of the undercount within each stratum using the profile log likelihood, thereby extending the work of Cormack (1992, Biometrics48, 567-576).

Biometry↗
PubMed1989

A consideration of the validity and reliability of suicide mortality data.

The question of the validity and reliability of suicide statistics may be considered at three levels: (1) Are suicide deaths misidentified or differentially identified across jurisdictions or over time? (2) To what degree are suicide deaths misidentified? and (3) Is the degree to which suicides are misidentified sufficient to threaten the validity of research based on suicide statistics? There is general agreement that suicides are likely to be undercounted, both for structural reasons (the burden-of-proof issue, the requirement that the coroner or medical examiner suspect the possibility of suicide) and for sociocultural reasons. There is also substantial anecdotal and empirical evidence suggesting that the mode of death for some true suicides is in fact certified as other than suicide. Overall, it does not seem that very many true nonsuicides are incorrectly certified as suicides. There is not, however, much agreement as to the degree to which true suicides are undercounted. At least some of the inconsistencies in the findings of different investigators arise because the validity of suicide certification seems to vary from place to place. But the source of apparent conflicts in many of the findings is undoubtedly the lack of a "gold standard" against which the verdicts of any given death certification process can be measured. At best, we can estimate that the sensitivity with which coroners and medical examiners certify true suicides varies from approximately 55% to 99%. A central question in estimating the sensitivity of suicide certification is this: What proportion of true suicides are either equivocal or likely to go unsuspected by the coroner or medical examiner? Very little has been done to investigate this issue. Yet the sensitivity of suicide certification clearly varies for equivocal versus unequivocal suicides. As shown in Table 1.2, specificity is also at issue when it comes to certifying equivocal cases. The final question--whether the degree of undercounting of suicide deaths is so great that it threatens the validity of research based on official statistics--is at the crux of the general concern about suicide certification. There are examples of studies in which conclusions based on crude comparisons of reported suicide statistics appear to be invalid. For the most part, these are comparisons among nations with substantially differing death certification procedures. When official statistics are interpreted with a degree of caution and an understanding of the source and direction of biases likely to affect the published rates, however, it seems unlikely that major conclusions based on these statistics will be in error.(ABSTRACT TRUNCATED AT 400 WORDS)

Cause of Death↗
PubMedDate not supplied

Underreporting of minority AIDS deaths in San Francisco Bay area, 1985-86.

A disproportionately high number of AIDS cases in the United States involve members of racial minorities. Even so, AIDS deaths of minority members may be undercounted. The completeness of reporting of AIDS deaths to the California AIDS Registry (ARS) among Hispanics, blacks, and whites in 1985 and 1986 from the San Francisco Bay Area was investigated. Death certificates listing AIDS as a cause of death or associated condition were identified and cross-checked with cases reported to ARS, current to December 1988. Death certificates were checked by hand for racial or ethnic classification using a definition of Hispanic based on information available on certificates. Three causes of undercounting in ARS were identified: a death was not reported as an AIDS case at all, an AIDS case was reported to ARS but the person was listed as still living, or an AIDS death was reported to ARS with a different racial or ethnic classification. The proportion of cases not reported at all was similar for all three racial-ethnic groups (5-8 percent). The proportion of deaths reported for persons listed in the registry as still living was 12 percent for Hispanics and 9 percent for blacks, compared with 5 percent for whites. For Hispanics, under-counting was largely due to ethnic misclassification. Twenty percent of Hispanics had been counted as white in the AIDS registry. In comparison, 4 percent of blacks and 1 percent of whites were misclassified by race. AIDS deaths among blacks and Hispanics may be undercounted, even in an area with good AIDS surveillance systems. This suggests that overrepresentation of minorities among AIDS cases in the United States may be even greater than indicated by current reporting data.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Quality of the family physician component of AMA Masterfile.

BACKGROUND: This investigation was undertaken to gain insight into the validity of the American Medical Association (AMA) Masterfile data. METHODS: Allopathic family physicians were chosen as the study population Omissions were picked up from by comparing the AMA list with the 1990 Ohio Academy of Family Physicians Foundation-Ohio Department of Health (OAFPF-ODH) census. Verification of the 1990 specialty and geographic location of allopathic family physicians not common to both files was achieved by sequentially (1) reviewing the AMA names against 1990 deletions from the 1985 OAFPF-ODH census, (2) contacting physicians directly by telephone, (3) verifying 1990 physician status with county medical personnel, and (4) mailing a brief questionnaire to each physician whose 1990 status remained unverified. RESULTS: The status of specialty and geographic location in 1990 was verified in 91 percent of names not common to both lists. Incorrect omissions (undercounts) and incorrect inclusions (overcounts) offset each other for both lists. Two groups of family physicians contribute to counting biases: family physicians who fulfill short-term goals by part-time practice in several locations, and family physicians who restrict their practice to a limited medical content area. CONCLUSIONS: Because of nearly equal offsetting of overcounting (incorrect inclusions) and under counting (incorrect omissions), the 1990 Ohio family physician AMA Masterfile data is adequate for work-force projections and policy studies when the county data are aggregated at the state level. The overcounting and undercounting for smaller areas or categories must still be studied, however. Application of the AMA Masterfile data of other geographic areas requires a knowledge of the components of undercounts and overcounts of the population being studied.

American Medical Association↗
PubMed1991

Total error in PES estimates of population.

"We describe a methodology for estimating the accuracy of dual systems estimates (DSE's) of population, census estimates of population, and estimates of undercount in the census. The DSE's are based on the census and a post-enumeration survey (PES). We apply the methodology to the 1988 dress rehearsal census of St. Louis and east-central Missouri and we discuss its applicability to the 1990 [U.S.] census and PES. The methodology is based on decompositions of the total (or net) error into components, such as sampling error, matching error, and other nonsampling errors. Limited information about the accuracy of certain components of error, notably failure of assumptions in the 'capture-recapture' model, but others as well, lead us to offer tentative estimates of the errors of the census, DSE, and undercount estimates for 1988. Improved estimates are anticipated for 1990." Comments are included by Eugene P. Ericksen and Joseph B. Kadane (pp. 855-7) and Kenneth W. Wachter and Terence P. Speed (pp. 858-61), as well as a rejoinder by Mulry and Spencer (pp. 861-3).

Americas↗
PubMed1995

Life expectancy in four U.S. racial/ethnic populations: 1990.

Previous estimates of life expectancy in the United States have not corrected for biases in population and mortality data, and no study has examined life expectancy in U.S. Asian/Pacific Islander and American Indian populations. We used information on population undercounts by race/ethnicity in the census and on misclassification of race/ethnicity on death certificates to calculate life expectancy for black, white, American Indian, and Asian men and women in the United States in 1990. Correction for undercount and misclassification had little effect on life expectancy estimates for whites, but it substantially decreased estimates for American Indians and Asians. Asian men had life expectancies of 82.0 years and Asian women 85.8 years--the highest life expectancies reported for any population in the world and beyond the limit predicted by some current theories.

Adolescent↗