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[Problems in improving the public health of a rural area based on a study of statistical data on population health].

The dynamics of health indices of the Khust District (Transcarpathian Province [correction of Zacarpathye region]) population was studied from 1970 through 1990. It is concluded that statistical data on the increase of morbidity are related to improvement of diagnostics of nosological entities related to increase of the availability of doctors, nursing personnel, number of beds in the district. Reserves of further medical services to the population are discussed.

Delivery of Health Care↗

Stapes surgery in the United States.

OBJECTIVE: A contemporary analysis of trends in the surgical management of otosclerosis in the United States is presented. DATA SOURCES: U.S. population demographics were obtained from the U.S. Census Bureau. Surgical case data was obtained from publications of the National Center for Health Statistics. Physician population statistics are published by the American Medical Association. DATA EXTRACTION: Available estimates for otologic operations are interpreted according to clinical setting used for data acquisition and surgical practice patterns. Linear regression of included data defines trends in operations performed. Population statistics are used to define changes in the incidence of surgical cases. CONCLUSIONS: The number of stapedectomy cases has declined over the past 30 years. During this same interval, the U.S. population (including the white population) and the number of surgeons has increased. This indicates that the incidence of surgical otosclerosis is declining. Although the true etiology of the decline is uncertain, widespread immunization for measles is a plausible hypothesis.

Adolescent↗

Population bases and statistical provision: towards a more flexible future?

In an increasingly complex and mobile society, there is a need for population estimates to be produced on a more flexible basis. Different uses of population data may require information to be output on different population bases, such as where people usually live ('usual residence') or where they are on a particular day ('population present'). This article explores many of the issues associated with defining 'the population'. Following consultation with data users, it outlines recommended population definitions that could facilitate a more flexible approach. Comparisons are made between the output bases produced from the 2001 Census and the more adaptable outputs potentially available in future if the recommended definitions were used.

Censuses↗

Application of maximum likelihood statistics for the population and family studies of inheritance of the chimpanzee R-C-E-F and V-A-B-D blood groups.

Maximum likelihood statistics were applied to the analysis of serological data to confirm the originally proposed genetic models of the chimpanzee R-C-E-F and V-A-B-D systems. Five hundred ninety-nine chimpanzees, including 81 parents of 114 offspring, were tested for R-C-E-F, and 60 parents of 80 offspring were tested for V-A-B-D blood groups. An estimation-maximization procedure was used to obtain maximum likelihood estimates and support intervals of the haplotype frequencies. For each haplotype, the null hypothesis of nonexistence was evaluated. The frequencies obtained by this method do not differ significantly from those calculated by the square root formula, but put these estimates on a statistically more rigorous footing.

Animals↗

Human population expansion and microsatellite variation.

Polymorphisms at di-, tri-, and tetranucleotide microsatellite loci have been analyzed in 14 worldwide populations. A statistical index of population expansion, denoted S(k), is introduced to detect historical changes in population size using the variation at the microsatellites. The index takes the value 0 at equilibrium with constant population size and is positive or negative according to whether the population is expanding or contracting, respectively. The use of S(k) requires estimation of properties of the mutation distribution for which we use both family data of Dib et al. for dinucleotide loci and our population data on tri- and tetranucleotide loci. Statistical estimates of the expansion index, as well as their confidence intervals from bootstrap resampling, are provided. In addition, a dynamical analysis of S(k) is presented under various assumptions on population growth or decline. The studied populations are classified as having high, intermediate, or low values of S(k) and genetic variation, and we use these to interpret the data in terms of possible population dynamics. Observed values of S(k) for samples of di-, tri-, and tetranucleotide data are compatible with population expansion earlier than 60,000 years ago in Africa, Asia, and Europe if the initial population size before the expansion was on the order of 500. Larger initial population sizes force the lower bound for the time since expansion to be much earlier. We find it unlikely that bottlenecks occurred in Central African, East Asian, or European populations, and the estimated expansion times are rather similar for all of these populations. This analysis presented here suggests that modern human populations departed from Africa long before they began to expand in size. Subsequently, the major groups (the African, East Asian, and European groups) started to grow at approximately same time. Populations of South America and Oceania show almost no growth. The Mbuti population from Zaire appears to have experienced a bottleneck during its expansion.

Animals↗

Frequency distribution of lymphatic filariasis microfilariae in human populations: population processes and statistical estimation.

This paper uses simple mathematical models and statistical estimation techniques to analyse the frequency distribution of microfilariae (mf) in blood samples from human populations which are endemic for lymphatic filariasis. The theoretical analysis examines the relationship between microfilarial burdens and the prevalence of adult (macrofilarial) worms in the human host population. The main finding is that a large proportion of observed mf-negatives may be 'true' zeros, arising from the absence of macrofilarial infections or unmated adult worms, rather than being attributable to the blood sampling process. The corresponding mf distribution should then follow a Poisson mixture, arising from the sampling of mf positives, with an additional proportion of 'true' mf-zeros. This hypothesis is supported by analysis of observed Wuchereria bancrofti mf distributions from Southern India, Japan and Fiji, in which zero-truncated Poisson mixtures fit mf-positive counts more effectively than distributions including the observed zeros. The fits of two Poisson mixtures, the negative binomial and the Sichel distribution, are compared. The Sichel provides a slightly better empirical description of the mf density distribution; reasons for this improvement, and a discussion of the relative merits of the two distributions, are presented. The impact on observed mf distributions of increasing blood sampling volume and extraction efficiency are illustrated via a simple model, and directions for future work are identified.

Animals↗

Calculation of survival curves and statistical comparison of two censored populations: a computer program in BASIC.

In experimental aging research the handling of censored data imposes a serious problem in the calculation of survival curves of partly censored populations and the statistical comparison of such populations. The presented computer program combines a method to calculate a corrected survival curve and a test to compare two censored populations. In both methods, the proportion of the animals that survive or die during an interval and the number at risk at the start of that interval is used in the calculation of relative survival or death during that interval. The program is written in an elementary BASIC and will run on practically every computer programmable in BASIC. The presented method can be used for testing the difference between survival characteristics of two animal populations but might also be employed in evaluating the effect of a medical treatment.

Aging↗

[Birth statistics for "standard populations". A basis for obstetric quality development].

Using standard populations like "standard-primipara" (normal pregnancy, singleton term delivery and cephalic presentation) and "caesarean secundapara" (previous caesarean section and second birth) as the basis for interunit comparisons of maternity care will control for differences in casemix that may be seen at different units, thereby increasing the validity of comparisons. Focusing on clinically meaningful subsets of the population may have the additional benefit of clarifying the relationship between everyday clinical decision making, and the statistics from medical birth registration. Birth registry data from Rigshospitalet, Hvidovre Hospital and Herning Centralsygehus 1993-1994 have been used to illustrate the association between local quality improvement activities, on the one hand, and rates of interventions and foetal outcome in "standard-primipara" on the other.

Adult↗

Analysis of neonatal and infant mortality data for the white population of the Witwatersrand.

Statistics of population size, number of births, and neonatal and infant mortality for the White populations of 10 Witwatersrand municipalities were studied. Sources of data were: (i) national statistics from the Central Statistical Services; and (ii) annual reports from the local authorities. The two sources correlated well for population size and number of births (r = 0,99), less so for infant deaths (r = 0,71), and not at all for neonatal deaths (r = 0,43). Causes of infant mortality were also studied, using national and local reports. Comparison of hospital records with those of the local Department of Health revealed significant coding errors in the recording of causes of death. The mechanisms for reporting births and deaths are discussed and suggestions for improvements in the system are made.

Death Certificates↗

Effective size and F-statistics of subdivided populations for sex-linked loci.

For a population subdivided into an arbitrary number (s) of subpopulations, each consisting of different numbers of separate sexes, with arbitrary distributions of family size and variable migration rates by males (dm) and females (df), the recurrence equations for inbreeding coefficient and coancestry between individuals within and among subpopulations for a sex-linked locus are derived and the corresponding expressions for asymptotic effective size are obtained by solving the recurrence equations. The usual assumptions are made which are stable population size and structure, discrete generations, the island migration model, and without mutation and selection. The results show that population structure has an important effect on the inbreeding coefficients in any generation, asymptotic effective size, and F-statistics. Gene exchange among subpopulations inhibits inbreeding in initial generations but increases inbreeding in later generations. The larger the migration rate, the greater the final inbreeding coefficients and the smaller the effective size. Thus if the inbreeding coefficient is to be restricted to a specific value within a given number of generations, the appropriate population structure (the values of s, dm, and df) can be obtained by using the recurrence equations. It is shown that the greater the extent of subdivision (large s, small dm and df), the larger the effective size. For a given subdivided population, the effective size for a sex-linked locus may be larger or smaller than that for an autosomal locus, depending on the sex ratio, variance and covariance of family size, and the extend of subdivision. For the special case of a single unsubdivided population, our recurrence equations for inbreeding coefficient and coancestry and formulas for effective size reduce to the simple expressions derived by previous authors.

Animals↗