PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Population Density--statistics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

49 records · Page 3Linked to original sources
PubMed1981

Computation of cancer incidence rates for defined small geographical areas--matching of numerator and denominator.

The authors present the problem of validity of numerator and pertinence of denominator for small geographical areas on sample of average annual crude incidence rates of stomach cancer in Slovenia during the period 1968--1974. At census in 1971 this country counted 1 727 137 of population. According to the residence of the patients the rates have been calculated for 60 municipalities, and besides for 29 so called "epidemiological regions", defined by their geographical and ethnic characteristics. Although in both instances great differences in incidence rates have been found, only a few areal units exhibited a significantly lower or higher rate from the national average. Specially areas with small population base "disappeared" in the average, although the value of the rate for them was rather low or high. A formula is presented by which at given rate for total country it is possible to determine the minimal size of population which still could provide estimation of statistically significant lower rate. Thus, for areas with small population a period of observation through many years is required in order to obtain the necessary minimal population base. The question is pointed out, whether this approach is reasonable as to the epidemiological interest, considering that some factors related to cancer may change during the long period of time. On the other hand, when merging small areas into larger ones, attention must be paid that these are not too heterogeneous as to their cancer incidence rate, geographical, ethnic, socio-economic and life-style features.

Humans↗
PubMed1976

Mathematical models for nonparametric inferences from line transect data.

A general mathematical theory of line transects is develoepd which supplies a framework for nonparametric density estimation based on either right angle or sighting distances. The probability of observing a point given its right angle distance (y) from the line is generalized to an arbitrary function g(y). Given only that g(O) = 1, it is shown there are nonparametric approaches to density estimation using the observed right angle distances. The model is then generalized to include sighting distances (r). Let f(y/r) be the conditional distribution of right angle distance given sighting distance. It is shown that nonparametric estimation based only on sighting distances requires we know the transformation of r given by f(O/r).

Animals↗
PubMed1984

Research design and analysis of data procedures for predicting body density.

Statistical methods used to develop body composition prediction equations were examined. Equations published in the 1960s and early 1970s have been called "population-specific" equations because they were developed on homogeneous samples. A major limitation of population-specific equations was a low ratio of subjects per variable, which reduces validity. The more recent method has been to develop "generalized" equations with large samples varying greatly in age and body fatness. The statistical models used for generalized equations were nonlinear regression analysis to account for the quadratic relation between body density and skinfold fat. Age was used as an independent variable to adjust for aging. Generalized equations exhibit accuracy consistent with population-specific equations and increase the generalizability of prediction. Future body composition research should focus on the cross-validation of published equations to define the limits of equation accuracy.

Adult↗
PubMed1984

Averaging population density.

Population density is a commonly quoted statistic. Almost no general descriptive summary of the population of an area is complete without a density listing, table or map. As each such density statistic is an average, it is worth considering what kind of average is being used. This article analyzes this and illustrates the effect of some alternative calculations using population density data for Great Britain; the findings, however, are of general validity.

Demography↗
PubMed2002

Periapical status, prevalence and quality of endodontic treatment in an adult French population.

AIM: The aim of this study was to determine the periapical status and the quality of root-canal treatment amongst an adult population attending the dental school in Nice, France during 1998. METHODOLOGY: Patients who attended the dental school for the first time during 1998 were included. Panoramic radiographs, taken by a trained radiology assistant, were used in this study. The periapical areas of all teeth with the exception of third molars, were examined and the technical quality of root fillings were evaluated for both apical extension and density. Statistical analyses were conducted using anova, Chi-square, Fisher's PLSD and Cohen's Kappa tests. RESULTS: The survey involved 344 patients: 180 females and 164 males. Males had significantly fewer natural remaining teeth than females (P<0.03). Similarly, the average number of root-filled teeth was lower for males (P<0.01). Nonroot-filled teeth (n=6126) had significantly fewer signs of periapical pathology than root-filled teeth (n=1429) (1.7% vs. 31.5%, P<0.0001). The majority of root fillings were poorly executed. There was a significant correlation between the presence of periapical pathology and inadequate root-canal fillings (P<0.001). CONCLUSIONS: The results of the present study indicate that many root-canal treatments were technically unsatisfactory in terms of quality and treatment outcome. There is a need for endodontic retreatment in the population examined.

Adult↗
PubMed2002

Reduced intravertebral bone marrow fat in HIV-infected men.

OBJECTIVE: To measure intravertebral bone marrow fat in HIV-infected men. DESIGN: A cross-sectional study of HIV-positive men, subcategorized by lipodystrophy and antiretroviral status, and healthy age- and body mass index (BMI)-matched HIV-negative controls. SETTING: A tertiary care academic medical institution. PATIENTS: Fifteen HIV-infected men and nine age- and BMI-matched healthy control subjects were recruited for bone density, intravertebral bone marrow fat, and body composition measurements. METHODS: Magnetic resonance spectroscopy was used to measure intravertebral marrow fat. Quantitative computed tomography was used to quantify visceral and subcutaneous fat. Dual energy X-ray absorptiometry was used to determine lumbar spine bone density. Statistical comparisons were performed according to HIV, lipodystrophy, and protease inhibitor (PI) exposure status. RESULTS: Intravertebral marrow fat was reduced in HIV-infected men (N = 15) compared with healthy HIV-negative controls (N = 9) (28.5 +/- 8.0 versus 37.3 +/- 12.5%, P = 0.04). Intravertebral bone marrow fat was most severely reduced in HIV-infected men with lipodystrophy compared with healthy HIV-negative controls (25.6 +/- 8.8% versus 37.3 +/- 12.5%, P = 0.04). Furthermore, nelfinavir (P = 0.02) was associated with decreased intravertebral marrow fat and indinavir (P < 0.05) was associated with increased intravertebral marrow fat in HIV-infected subjects. CONCLUSION: We demonstrated reduced intravertebral marrow fat in HIV-infected men using magnetic resonance spectroscopy. Notably, reduced marrow fat occurred in the setting of reduced bone density and may be affected by specific PI and lipodystrophy status. Further studies are necessary to determine the relationship between marrow fat and osteopenia and the effect of antiretroviral therapy on marrow fat in this population.

Absorptiometry, Photon↗