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PubMed1995

Application of statistical inference techniques in health information management.

We have demonstrated that objective comparisons can be made using accepted statistical techniques. We have also shown that you can apply tests which don't meet the basic assumptions and still obtain valid results, in most cases. This robustness of statistics tests is particularly helpful with the type of data and analysis that health information management professionals typically deal with, where exactness of the results is not crucial. You can perform a quick analysis using simple statistical tools and obtain a P value that is fairly close to what it would be if you selected the tests more stringently. The examples of inferential statistics in this article demonstrate how to select tests based on characteristics of the data and how to interpret the results. The kinds of statistical analysis that can be performed in health information management are numerous. Below are some other ideas on how to use inferential statistics in HIM practice. 1. Set up an ordinal scale to evaluate coding accuracy to evaluate coders: Score 1 means the correct code was assigned for the principal diagnosis and only minor errors in coding among secondary diagnoses. Score 2 means the correct code was assigned for the principal diagnosis, but there are omissions or major errors among secondary diagnoses. Score 3 means a minor error in coding the principal diagnosis and only minor errors in secondary diagnoses. Score 4 means a minor error in coding the principal diagnosis and major errors or omissions in secondary diagnoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed2001

Statistical inference of progressivity dominance: an application to health care financing distributions.

This paper employs a distribution-free statistical test suitable for comparisons based on dependent samples to analyse changes in health care financing distributions on Finnish data. In distinction to the more general summary index approach used in most studies of progressivity measurement, the difference between the Lorenz curve of income inequality and the concentration curves of various taxes and payments is used to evaluate progressivity dominance and changes in progressivity. Sample weights are applied to account for the effect of sampling design and non-response. The analysis demonstrates that the dominance approach can be successfully applied to various types of distributional problems besides comparisons concerning differences in income distributions. As an empirical application the paper presents estimation results for the progressivity of various health care financing sources using data from the 1987 and 1996 Finnish Health Care Surveys.

Family Characteristics↗
PubMed2005

Statistical inferences about the mechanism of action in carcinogenicity studies.

An innovative approach to dose-response modeling provides statistical insight into the relative likelihood of different mechanisms of action in cancer dose-response studies. Two illustrative examples are given based on time-to-tumor data on mammary fibroadenoma and adenocarcinoma in female Sprague-Dawley rats using 34 different dose metrics. The likelihood for the study outcome was calculated for each dose metric and compared with the background likelihood using a likelihood-ratio test. In the first example, fibroadenomas were strongly related to the presence or absence of mammary secretory activity, galactoceles, pituitary tumors, and abnormal diestrous days in weeks 1 to 26. Adenocarcinomas were the most strongly related to the number and percentage of abnormal estrous days. In these examples, the usual dose metric based on the dietary concentration of the pesticide had some explanatory ability but not nearly as much as the dose metrics more directly related to hormonal mechanisms of action.

Animals↗
PubMed2005

Influence of air-sea fluxes on chlorine isotopic composition of ocean water: implications for constancy in delta37Cl--a statistical inference.

The behaviors of chlorine isotopes in relation to air-sea flux variables have been investigated through multivariate statistical analyses (MSA). The MSA technique provides an approach to reduce the data set and was applied to a set of 7 air-sea flux variables to supplement and describe the variation in chlorine isotopic compositions (delta37Cl) of ocean water. The variation in delta37Cl values of surface ocean water from 51 stations in 4 major world oceans--the Pacific, Atlantic, Indian and the Southern Ocean has been observed from -0.76 to +0.74 per thousand (av. 0.039+/-0.04 per thousand). The observed delta37Cl values show basic homogeneity and indicate that the air-sea fluxes act differently in different oceanic regions and help to maintain the balance between delta37Cl values of the world oceans. The study showed that it is possible to model the behavior of chlorine isotopes to the extent of 38-73% for different geographical regions. The models offered here are purely statistical in nature; however, the relationships uncovered by these models extend our understanding of the constancy in delta37Cl of ocean water in relation to air-sea flux variables.

Air↗
PubMed1990

Statistical inference on mean dioptric power: hypothesis testing and confidence regions.

It has not hitherto been possible to apply formal methods of statistical analysis to data on dioptric powers. The solution to the basic statistical problem is now provided in this paper. Recognition of the matric-variate nature of dioptric power allows calculation of sample means and variance-covariances. These in turn can be used to calculate a statistic for testing hypotheses on population means and for obtaining confidence regions for those means. In a graphical representation of dioptric power the confidence region turns out to be an ellipsoid centred on the mean of the sample of dioptric powers. The theory is illustrated by means of numerical examples. Singularity of the variance-covariance matrix may occur especially when the sample is small. When it does occur it is the cause of some difficulty in applying the statistics. Nevertheless singularity is rare in practical situations and can usually be avoided simply by increasing the size of the sample. Singularity, therefore, is not treated fully in this paper. Dioptric power is essentially four-dimensional in character but in practice a three-dimensional subspace is almost always sufficient. To avoid the difficulty of having to represent four-dimensional shapes and to avoid the complication of singularity (which is the rule rather than the exception in practice in four-space) only the common three-dimensional problem is considered in detail.

Analysis of Variance↗
PubMed2005

A regulatory perspective on choice of margin and statistical inference issue in non-inferiority trials.

Without a placebo arm, any non-inferiority inference involving assessment of the placebo effect under the active control trial setting is difficult. The statistical risk for falsely concluding non-inferiority cannot be evaluated unless the constancy assumption approximately holds that the effect of the active control under the historical trial setting where the control effect can be assessed carries to the noninferiority trial setting. The constancy assumption cannot be checked because of missing the placebo arm in the non-inferiority trial. Depending on how serious the violation of the assumption is thought to be, one may need to seek an alternative design strategy that includes a cushion for a very conservative non-inferiority analysis or shows superiority of the experimental treatment over the control. Determination of the non-inferiority margin depends on what objective the non-inferiority analysis is intended to achieve. The margin can be a fixed margin or a margin functionally defined. Between-trial differences always exist and need to be properly considered.

Biopharmaceutics↗