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Results for “Spatial Distribution--statistics”

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PubMed1986

Fertility and adaptation: Indochinese refugees in the United States.

"Levels of fertility among Indochinese refugees in the United States are explored in the context of a highly compressed demographic transition implicit in the move from high-fertility Southeast Asian societies to a low-fertility resettlement region. A theoretical model is developed to explain the effect on refugee fertility of social background characteristics, migration history and patterns of adaptation to a different economic and cultural environment controlling for marital history and length of residence in the U.S." The chief source for the data and analyses is the Indochinese Health and Adaptation Research Project (IHARP), San Diego State University. "Multiple regression techniques are used to test the model which was found to account for nearly half of the variation in refugee fertility levels in the United States. Fertility is much higher for all Indochinese ethnic groups than it is for American women; the number of children in refugee families is in turn a major determinant of welfare dependency. Adjustments for rates of natural increase indicate a total 1985 Indochinese population of over one million, making it one of the largest Asian-origin populations in the United States."

Acculturation↗
PubMed1979

[Some remarks about the spatial differentiation of fertility in Poland].

"Some problems are discussed in connection with the estimation and interpretation of regression equations. Stability in time is suggested as one of the criteria of goodness of fit.... Several regression equations are estimated giving the gross reproduction rate as a linear function of the proportion of economically active females outside agriculture (SUMMARY IN ENG, RUS)

Birth Rate↗
PubMed1986

Factor analysis of some socio-economic and demographic variables for Bangladesh.

The author carries out an exploratory factor analysis of some socioeconomic and demographic variables for Bangladesh using the classical or common factor approach with the varimax rotation method. The socioeconomic and demographic indicators used in this study include literacy, rate of growth, female employment, economic development, urbanization, population density, childlessness, sex ratio, proportion of women ever married, and fertility. The 18 administrative districts of Bangladesh constitute the unit of analysis. 3 common factors--modernization, fertility, and social progress--are identified in this study to explain the correlations among the set of selected socioeconomic and demographic variables.

Asia↗
PubMedDate not supplied

[A comparison of complete and truncated birth histories to measure fertility and child mortality].

"During the latter part of 1986, national probability sample surveys of women of reproductive ages were carried out in... Peru and the Dominican Republic. These surveys were made as part of the Demographic Health Surveys project (DHS). In each country, one survey was conducted with the standard core questionnaire developed for DHS; the other survey was based on an experimental questionnaire. The major difference between the two questionnaires is the inclusion in the experimental one of a monthly calendar, which records pregnancies, contraceptive use, reasons for contraceptive discontinuation, breastfeeding, post-partum amenorrhea, post-partum abstinence, women's employment and place of residence for the period 1981-1986. This paper presents results from the first stage of the analysis of the Peruvian data: a comparison of basic characteristics of the two samples and an assessment of the completeness of reporting of recent births and infant and child deaths, i.e., a comparison of information in the truncated and full birth histories." (SUMMARY IN ENG)

Americas↗
PubMed1983

Birthweights in Goroka and Kainantu Hospitals.

Birthweight data for 4474 live, healthy, singleton, full-term births of 2000g or over were analysed. The mean birthweights were 3136 +/- 445g at Goroka, and 3106 +/- 473g at Kainantu. Birthweights varied with sex, region of maternal origin, season and birth order, but not with year. Significant influences on Goroka birthweight values were, in order of importance, birth order, sex and season.

Birth Order↗
PubMed2002

Spatial distribution and sampling plans for Mesoplatys ochroptera (Coleoptera: Chrysomelidae) on sesbania.

With the widespread introduction of the nitrogen-fixing legume sesbania, Sesbania sesban (L.) Merril, in agroforestry systems, the defoliating beetle Mesoplatys ochroptera Stål has become a serious pest of the trees in Africa. To determine within-field and within-plant spatial distribution of M. ochroptera on both seedlings and trees of sesbania, distribution statistics were computed using Iwao's mean crowding regression model. In 1- to 3-mo-old seedlings, the model accounted for 29.8, 32.2, and 61.0% of the variation observed in mean crowding to mean relationships in egg masses, larvae and adults, respectively. The model slopes of the regression were greater than unity for all stages indicating aggregated spatial distribution. Values of the intercept were greater than zero for egg masses, larvae and adults indicating that the basic components of the population are groups of individuals. The highest density (>80%) of mating and feeding adults was found in the upper third of 1- to 2-mo-old seedlings, while most of the egg masses were found in the lower half of seedlings. In trees, >60% of the individuals of all stages were found in the lower third of the foliage canopy, while <10% were found in the upper third. Sampling adults was found to be easier and gave better density estimates of M. ochroptera population than egg masses and larvae. Therefore, sampling plans useful for population studies and decision-making in pest management were developed for adults.

Animals↗
PubMed2001

Two-dimensional versus three-dimensional cell counting: a practical perspective.

In recent years, it has been argued by some neuroanatomists that three-dimensional (3-D) counting approaches must be used in studies of neural systems, so that 'unbiased' counts of neurons can be obtained. By contrast, two-dimensional (2-D) cell-counting methods are said to be 'assumption-based' and to yield inaccurate results. Working from the premise that all scientific methodologies are assumption-based and suffer from inherent biases, the current review considers the relative strengths and weaknesses of 2-D versus 3-D counting approaches. This comparison is from the standpoint of predictive performance with respect to bias, variance and fidelity to the actual spatial arrangements of cells in the tissue under study. When these considerations are taken, together with the human resources that are required in using either methodology, 2-D methods offer more practical alternatives that might even provide more scientifically accurate estimates compared with their 3-D counterparts.

Animals↗
PubMed1997

Analysis of phosphorescence in heterogeneous systems using distributions of quencher concentration.

A continuous distribution approach, instead of the traditional mono- and multiexponential analysis, for determining quencher concentration in a heterogeneous system has been developed. A mathematical model of phosphorescence decay inside a volume with homogeneous concentration of phosphor and heterogeneous concentration of quencher was formulated to obtain pulse-response fitting functions for four different distributions of quencher concentration: rectangular, normal (Gaussian), gamma, and multimodal. The analysis was applied to parameter estimates of a heterogeneous distribution of oxygen tension (PO2) within a volume. Simulated phosphorescence decay data were randomly generated for different distributions and heterogeneity of PO2 inside the excitation/emission volume, consisting of 200 domains, and then fit with equations developed for the four models. Analysis using a monoexponential fit yielded a systematic error (underestimate) in mean PO2 that increased with the degree of heterogeneity. The fitting procedures based on the continuous distribution approach returned more accurate values for parameters of the generated PO2 distribution than did the monoexponential fit. The parameters of the fit (M = mean; sigma = standard deviation) were investigated as a function of signal-to-noise ratio (SNR = maximum signal amplitude/peak-to-peak noise). The best-fit parameter values were stable when SNR > or = 20. All four fitting models returned accurate values of M and sigma for different PO2 distributions. The ability of our procedures to resolve two different heterogeneous compartments was also demonstrated using a bimodal fitting model. An approximate scheme was formulated to allow calculation of the first moments of a spatial distribution of quencher without specifying the distribution. In addition, a procedure for the recovery of a histogram, representing the quencher concentration distribution, was developed and successfully tested.

Light↗
PubMed1995

Age-prevalence and household clustering of Strongyloides stercoralis infection in Jamaica.

The epidemiology of Strongyloides stercoralis was studied in families of clinical (reference) cases and their neighbours at endemic foci in Jamaica. Thirteen foci were studied based on the place of residence of a reference case. For each household of a reference case, the 4 most proximal neighbourhood households (spatial controls) were included in the study. Out of 312 persons contacted 244 were followed up using questionnaires, stool examination and serology. Prevalence of infection based on stool examination was 3.5% and on ELISA 24.2%. Prevalence increased with age but was not related to gender. Reference cases were significantly older than the general study population. The prevalence of infection based on both serology and stool examination was significantly higher in reference than in neighbouring households (the reference cases, themselves, were not included in the analysis). Furthermore, prevalence of infection was highest among persons who shared a bedroom with a reference case and decreased significantly with increasing spatial separation. This is indicative of close contact transmission which has not been previously shown for a geohelminth, but which is common among microparasites.

Adolescent↗
PubMed1992

Assessment of the spatial occurrence of childhood leukaemia mortality using standardized rate ratios with a simple linear Poisson model.

Reports of a suspected cluster of childhood leukaemia cases in West Central Phoenix have led to a number of epidemiological studies in the geographical area. We report here on a death certificate-based mortality study, which indicated an elevated rate ratio of 1.95 during 1966-1986, using the remainder of the Phoenix standard metropolitan statistical area (SMSA) as a comparison region. In the process of analysing the data from this study, a methodology for dealing with denominator variability in a standardized mortality ratio was developed using a simple linear Poisson model. This new approach is seen as being of general use in the analysis of standardized rate ratios (SRR), as well as being particularly appropriate for cluster investigations.

Adolescent↗
PubMedDate not supplied

[Cartography of epidemiologic data. The principal methods of making continuous data discrete and their importance in cartographic representation].

The cartographic representation of continuous quantitative data is often required in studies of the spatial distribution of health indicators. It imposes a succession of choices which directly affect the result obtained. The conversion of continuous data to discrete data is one of the most important steps in the development of epidemiological maps. This article presents the methods currently used to make data discrete, discusses the advantages and disadvantages of each method and assesses their appropriateness for various situations. As an example, and for comparison purposes, we mapped the same series of statistics (relative rates of avoidable male deaths, "associated with the health care system", for "employment zones" in France from 1988 to 1992), using each of the methods discussed.

Algorithms↗