1,721,061 research outputs found
Statistical aspects of the estimation of reference limits
No full textThis paper deals with some basic statistical issues arising from biological monitoring. Data description, Gaussianity tests, outlier identification, parametric and non-parametric estimates of fractiles and their standard errors, and parametric estimate of the one tail upper side tolerance interval are treated and exemplified using two data sets. Sample size and power determination are considered in terms of the cut-off point of the diagnostic quantitative test
La sintesi numerica dei dati statistici
No full textThe paper describes the methods currently used for numerical synthesis of statistical data. A review is made of the main properties of the various statistical indices required to describe the central tendency, dispersion and shape of distribution of values. Mode, median, arithmetic mean, harmonic and geometric mean, range, quantiles and standard deviation, asymmetry and kurtosis indices are described and discussed using data drawn from practical experience. Special attention is paid to the errors most frequently incurred using these methods. An appendix supplies details of some of the mathematical properties of the operators described
Valori di riferimento ed intervalli di tolleranza
No full textStatistical aspects of tolerance intervals estimation are considered and tolerance coefficients for unilateral and central intervals are derived for normally distributed biological variables. The difference between confidence and tolerance interval is explained and application to biological and environmental monitoring, as well as applications to reference values estimation, are exemplified. Tables of unilateral and central coefficients are also produced and reported for different sample dimensions, confidence, and tolerance levels
Elementi di calcolo delle probabilità : 2
No full textThis is the second part of an introduction to probability calculation and covers basic concepts such as conditional and simple probabilities and independent events and also a definition of two fundamental laws, those of addition and multiplication, which permit a correct combination of probabilities. Explanation of probability concepts and ideas is illustrated with the aid of examples from the field of screening tests. Bayes theorem is derived by applying the addition and multiplication laws to conditional and simple probabilities
Elementi di calcolo delle probabilità : 1
No full textThis is the first of a series of articles on probability calculation, consisting of a simple introduction to the definitions of probability. A brief historical background explains some of the reasons for the delay in the development of probability calculation and recalls the main problems that had to be faced, the solution of which marked the birth of the theory of probability. Classical, frequentist and subjective approaches are addressed and their relative merits and weaknesses are discussed
ROC curve analysis and medical decision making : what's the evidence that matters for an evidence-based diagnosis?
No full textROC curve analysis and medical decision making : what’s the evidence that matters for evidence-based diagnosis?
No full textThe cases of accident in the ceramic tile industry in relation to the age and job seniority of the workers = Il fenomeno infortunistico nell’industria della ceramica per piastrelle in relazione all’età e all’anzianità occupazionale dei lavoratori
No full textA study was made of 3,368 workers in 36 ceramic plants in the Scandiano area (Reggio Emilia, Italy) during the year 1990; 403 had an accident during the observation period. The incidence and severity of the accident were correlated to age, job (low, intermediate, high accident risk), duration of employment as at 1.1.1990 (> 24, 12-24, > 24, 12-24, 24 months category were 1.5 (1.1-2.0), 1.7 (1.3-2.2), 2.1 (1.6-2.8) respectively. Severity: the mean RIDIT of the > 44-year-old vs < 30-year-old workers was 0.6 (0.53-0.67)
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