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At least 847 records · Page 47Linked to original sources
PubMed2007

Modeling the probability distribution of positional errors incurred by residential address geocoding.

BACKGROUND: The assignment of a point-level geocode to subjects' residences is an important data assimilation component of many geographic public health studies. Often, these assignments are made by a method known as automated geocoding, which attempts to match each subject's address to an address-ranged street segment georeferenced within a streetline database and then interpolate the position of the address along that segment. Unfortunately, this process results in positional errors. Our study sought to model the probability distribution of positional errors associated with automated geocoding and E911 geocoding. RESULTS: Positional errors were determined for 1423 rural addresses in Carroll County, Iowa as the vector difference between each 100%-matched automated geocode and its true location as determined by orthophoto and parcel information. Errors were also determined for 1449 60%-matched geocodes and 2354 E911 geocodes. Huge (> 15 km) outliers occurred among the 60%-matched geocoding errors; outliers occurred for the other two types of geocoding errors also but were much smaller. E911 geocoding was more accurate (median error length = 44 m) than 100%-matched automated geocoding (median error length = 168 m). The empirical distributions of positional errors associated with 100%-matched automated geocoding and E911 geocoding exhibited a distinctive Greek-cross shape and had many other interesting features that were not capable of being fitted adequately by a single bivariate normal or t distribution. However, mixtures of t distributions with two or three components fit the errors very well. CONCLUSION: Mixtures of bivariate t distributions with few components appear to be flexible enough to fit many positional error datasets associated with geocoding, yet parsimonious enough to be feasible for nascent applications of measurement-error methodology to spatial epidemiology.

Censuses↗
PubMed1998

Spatial distribution patterns of Echinococcus multilocularis (Leuckart 1863) (Cestoda: Cyclophyllidea: Taeniidae) among red foxes in an endemic focus in Brandenburg, Germany.

Over a period of 40 months, 4374 foxes were randomly sampled from an area located in northwestern Brandenburg, Germany, and examined parasitologically for infections with Echinococcus multilocularis. Spatial analysis of the origin of infected animals identified two (one central and one southeastern) high-endemic foci with an estimated prevalence of 23.8%. By contrast, a prevalence of 4.9% was found in the remaining (low-endemic) area. The prevalences among juvenile and adult foxes were compared in the high-endemic and the low-endemic areas. To analyse the central high-endemic focus further, the random sample was stratified by zones representing concentric circles with a radius of 13 km (zone 1) or x(n-1) + 7 km for the remaining three zones from the apparent centre of this focus (anchor point). Prevalences calculated for each zone showed a decrease from zone 1 (18.8%) to zone 4 (2.4%) with significant differences for all zones but zones 3 and 4. The relative risk of an infection decreased rapidly in a distance range of 26 km around the high-endemic focus, whereas the relative risk remained unchanged within a distance of 5 km around the anchor point. The importance of heterogeneous spatial distribution patterns for the diagnosis and epidemiology of the infection is discussed.

Age Distribution↗
PubMed2004

Breast cancer incidence and its possible spatial association with pesticide application in two counties of England.

BACKGROUND: This study examines the spatial distribution of breast cancer incidence in Lincolnshire and Leicestershire, and its association with the application of selected pesticides. METHODS: The Black-White (BW) join-count statistic and Moran I coefficient were used to investigate the localized distribution of breast cancer. Linear regression techniques were applied to examine the association between the breast cancer incidence rate and pesticide application. RESULTS: The results from the BW join-count test and the Moran I coefficient test showed no overall evidence of localized distribution, 'clusters', of breast cancer. The regression analyses showed no sign of spatial association between breast cancer and application of pesticides in the urban areas as expected. The findings, however, did reveal a spatial association between the breast cancer incidence rates and the application of three selected pesticides [Aldicarb, Atrazine and Lindane (thought to potentially mimic oestrogen)] in rural Leicestershire. No such association was seen in Lincolnshire. CONCLUSIONS: Pesticides vary significantly in their spatial application. Overall, consistent associations between breast cancer incidence rates and the selected pesticides were not found, although the ecological study design has limitations and these are discussed. This approach is able to rule out strong associations; assessment of smaller risk would require a large and expensive study in individuals. The results of this study, although derived in the UK, have significance to the debate concerning the possibility of environmental compounds that mimic oestrogen and their consequences for human health.

Aged↗
PubMed1998

Population change in the Great Plains since 1950 and the consequences of selective migration.

This "study was initiated to explore the causes and consequences of persistent population loss in the Great Plains region [of the United States]. After classifying all counties by their growth patterns over the past five decades, we developed a typology that categorized counties based on the direction and magnitude of their population change.... We use this typology to explore the correlates of residential population change, and to examine the explanatory power of the variables found to be statistically significant."

Americas↗
PubMed1997

Nonmetro elders better off than metro elders on some measures, not on others.

The author examines characteristics of the nonmetropolitan elderly in the United States. "A larger share of the nonmetro population was age 60 and older (18 percent) in 1996 than the metro population (15 percent). At ages 75 and older, half of all elderly persons are living alone. This is associated with a greater likelihood of being poor: 42 percent of nonmetro persons age 75 and older were poor or near-poor, compared with 28 percent of their metro counterparts."

Adult↗
PubMed2006

The geography of self-injury: spatial patterns in attempted and completed suicide.

This study uses hospital discharge data, death certificates and medical examiner data for New Jersey for 1999-2001 to investigate whether fatal and non-fatal self-injury exhibit similar geographic patterns. Findings show that the demographic characteristics of individuals committing fatal and non-fatal self-injury are quite different. Furthermore, attempted and completed suicides have a somewhat different geographical pattern. Municipality-level determinants of suicide and non-fatal self-injury were estimated in two separate models. While measures of isolation such as low population density and high proportions of households with only one member were predictive of completed suicides, non-fatal self-injury was related to unemployment and median age. Both types of self-injury were more common in municipalities which lost population between 1990 and 2000, and where divorce rates were high. Population-based suicide prevention efforts should be aided by the knowledge that although there are some similarities in the spatial pattern of completed and attempted suicides, there are some important differences in significant determinants.

Adolescent↗
PubMed2002

Associations between indicators of livestock farming intensity and incidence of human Shiga toxin-producing Escherichia coli infection.

The impact of livestock farming on the incidence of human Shiga toxin-producing Escherichia coli (STEC) infection was assessed by using several livestock density indicators (LDI) that were generated in a systematic approach. A total of 80 LDI were considered suitable proxy measures for livestock density. Multivariate Poisson regression identified several LDI as having a significant spatial association with the incidence of human STEC infection. The strongest associations with human STEC infection were the ratio of beef cattle number to human population and the application of manure to the surface of agricultural land by a solid spreader and by a liquid spreader. This study demonstrates the value of using a systematic approach in identifying LDI and other spatial predictors of disease.

Animals↗
PubMed1987

Variation in lymphoma incidence within Yorkshire Health Region.

The spatial distribution of new cases of lymphoma occurring in Yorkshire between 1978 and 1982 has been studied. Administrative districts were used as the basis for analysis and differences in age standardised incidence rates between districts were determined. Excessive rates for NHL were found to occur in Scarborough, York and Leeds districts. In addition an analysis contrasting broadly urban and rural districts showed an excess of NHL in rural areas, particularly of the follicular subtypes.

Adolescent↗
PubMed2006

Geostatistical analysis of disease data: accounting for spatial support and population density in the isopleth mapping of cancer mortality risk using area-to-point Poisson kriging.

BACKGROUND: Geostatistical techniques that account for spatially varying population sizes and spatial patterns in the filtering of choropleth maps of cancer mortality were recently developed. Their implementation was facilitated by the initial assumption that all geographical units are the same size and shape, which allowed the use of geographic centroids in semivariogram estimation and kriging. Another implicit assumption was that the population at risk is uniformly distributed within each unit. This paper presents a generalization of Poisson kriging whereby the size and shape of administrative units, as well as the population density, is incorporated into the filtering of noisy mortality rates and the creation of isopleth risk maps. An innovative procedure to infer the point-support semivariogram of the risk from aggregated rates (i.e. areal data) is also proposed. RESULTS: The novel methodology is applied to age-adjusted lung and cervix cancer mortality rates recorded for white females in two contrasted county geographies: 1) state of Indiana that consists of 92 counties of fairly similar size and shape, and 2) four states in the Western US (Arizona, California, Nevada and Utah) forming a set of 118 counties that are vastly different geographical units. Area-to-point (ATP) Poisson kriging produces risk surfaces that are less smooth than the maps created by a naïve point kriging of empirical Bayesian smoothed rates. The coherence constraint of ATP kriging also ensures that the population-weighted average of risk estimates within each geographical unit equals the areal data for this unit. Simulation studies showed that the new approach yields more accurate predictions and confidence intervals than point kriging of areal data where all counties are simply collapsed into their respective polygon centroids. Its benefit over point kriging increases as the county geography becomes more heterogeneous. CONCLUSION: A major limitation of choropleth maps is the common biased visual perception that larger rural and sparsely populated areas are of greater importance. The approach presented in this paper allows the continuous mapping of mortality risk, while accounting locally for population density and areal data through the coherence constraint. This form of Poisson kriging will facilitate the analysis of relationships between health data and putative covariates that are typically measured over different spatial supports.

Cluster Analysis↗