Re: "A statistical method for evaluating suicide clusters and implementing cluster surveillance".
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Algorithms↗
Biomedical subjects
D Böhning
Publications and source records attributed to D Böhning.
The area between curves (ABC)--measure in nutritional anthropometry.
This paper considers a statistic--recently suggested by Mora--for the deviation of a sample distribution from a reference distribution which typically arises in anthropometry when using the nutritional indicators height/age, weight/age or weight/height. The statistic measures the area between curves (ABC) and stands for the mass of the sample distribution which is not covered by the reference distribution. The paper provides a statistical framework for the ABC and includes some minor corrections of Mora's original paper. For the normal distribution situation with common or different variances, formulae are derived which include a partition of ABC into parts corresponding to malnourished and well-nourished groups. However, the main result is a non-parametric generalization of the ABC, motivated by the fact that the nutritional indicators often have skewed distributions with heavier left tails. Non-parametric statistical inference is provided by linking the ABC to the Kolmogorov-Smirnov statistic.
Analysis of Variance↗
Computer-assisted analysis of mixtures (C.A.MAM): statistical algorithms.
This paper presents various algorithmic approaches for computing the maximum likelihood estimator of the mixing distribution of a one-parameter family of densities and provides a unifying computer-oriented concept for the statistical analysis of unobserved heterogeneity (i.e., observations stemming from different subpopulations) in a univariate sample. The case with unknown number of population subgroups as well as the case with known number of population subgroups, with emphasis on the first, is considered in the computer package C.A.MAN (Computer Assisted Mixture Analysis). It includes an algorithmic menu with choices of the EM algorithm, the vertex exchange algorithm, a combination of both, as well as the vertex direction method. To ensure reliable convergence, a step-length menu is provided for the three latter methods, each achieving monotonicity for the direction of choice. C.A.MAN has the option to work with restricted support size-that is, the case when the number of components is known a priori. In the latter case, the EM algorithm is used. Applications of mixture modelling in medical problems are discussed.
Algorithms↗
Seasonal variation of wasting and stunting in preschool children during a three-year community-based nutritional intervention study in northeast Thailand.
A nutritional intervention project was undertaken for three years in four villages located in a relatively prosperous irrigation area in northeast Thailand where sub-clinical undernutrition is still prevalent. Data were collected at each measuring pont from approximately 270 preschool children in four intervention villages. Approximately 120 children in three other villages in the same area served as controls for each measuring point. Various activities such as teaching nutrition, introducing supplementary feeding, and using and understanding weight charts, as well as home visits, were carried out in the intervention villages. An obvious improvement in the nutritional status of children in the intervention villages could be observed only after two years and nine months. In order that immediate action could be taken when a child was found to be undernourished or at risk of becoming undernourished in the near future, the nutritional indicator weight-for-height was used to assess the children's nutritional status. However, the best indicator determining the impact of the project was height-for-age. Intervention measures were successful in diminishing marked seasonal variations in the nutritional status observed in the study area. Statistical methods are given to evaluate a prospective study based on an incomplete repeated measure method.
Age Factors↗
Relationship of the morbidity of under-fives to anthropometric measurements and community health intervention.
In a 3-year prospective morbidity study in seven villages of northeast Thailand the health of preschool children was assessed every alternate week by questioning the mothers. The nutritional status was determined by weight-for-age, weight-for-height and height-for-age every third month. In four villages active measures were undertaken to improve the health and nutritional status of the children. A child had an average of 2.5 illness episodes and was ill 14.1 days per year. More than 80% of all illness episodes could be accounted to ill-defined infections such as fever and cough with only 5.2% accountable to diarrhoea. A marked decline in the rate of illness episodes was observed in communities where cooperation was good. Weight-for-height is a better indicator for determining children at risk of falling ill than weight-for-age and height-for-age. The duration of illness episodes was not related to the nutritional status.
Body Height↗
Confidence interval estimation of a rate and the choice of sample size.
The problem of estimating a rate or proportion is considered. Four methods for constructing an approximate confidence interval are discussed and compared via a simulation study. The most accurate method is found. Also, for each method a sharp upper bound (dependent only on the sample size) is given for the length of the confidence interval. By choosing an appropriate sample size this bound enables the practitioner to achieve a prespecified maximum length for the confidence interval without knowing the population rate. The striking result is that the most accurate method has the smallest bound, thus requiring the least sample units.
Computer Simulation↗
Human serum proteins indicative for the nutritional status and serum proteinase inhibitors in uncomplicated falciparum malaria.
The serum proteins supposed to be indicative of the nutritional status, albumin, prealbumin and transferrin, as well as the serum proteinase inhibitors alpha 1-protease inhibitor (alpha 1-antichymotrypsin (Ach) and alpha 2-macroglobulin (alpha 2M) were measured in 14 Thai males suffering from uncomplicated falciparum malaria on the day of admission and after treatment with mefloquin on the 2nd, 28th and 63rd day. The same serum proteins had been determined from 31 healthy Thai males. Upon admission albumin and prealbumin concentrations had been lower and Ach higher in malaria patients compared with healthy Thai males. A significantly higher alpha 1 PI value was observed on the day of admission compared with the 28th day of the malaria patients. Only on the day of admission and only for the patients was a statistically significant negative linear regression found for albumin and prealbumin with Ach and a positive correlation for prealbumin with alpha 2 M as well as for albumin and transferrin correlated with alpha 1 PI. In well-nourished malaria patients the synthesis of the "acute phase reactants", alpha 1 PI and Ach, might be enhanced and in a reverse relationship the synthesis of albumin, pre-albumin and transferrin depressed.
Animals↗