Nonparametric statistics
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The paper presents a brief overview of statistical methods used in clinical and experimental medicine, ranging from basic indicators and parameters of descriptive statistics and hypotheses testing (parametric as well as non-parametric methods) to a description of the most frequently used multivariate methods in medical scientific publications, to logistic regression. The paper also describes Principle Component Analysis (PCA), which is one of the methods used to decrease a data dimensionality. The proper use of statistical methods is demonstrated on specific clinical cases.
- MeSH
- analýza hlavních komponent MeSH
- analýza rozptylu MeSH
- interpretace statistických dat MeSH
- logistické modely MeSH
- multivariační analýza MeSH
- neparametrická statistika MeSH
- regresní analýza MeSH
- statistika jako téma * MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- přehledy MeSH
The submitted paper terminates the series of eight articles on the application of non-parametric methods in medicine, which were published in this journal in 1990-1991. Attention is drawn, on the one hand, to the urgent need of knowledge of mathematical and statistical methods, on the other hand, to the fact that proper processing of experimental data is not guaranteed by the use of computer technique alone, the complexity and numerical correctness of calculations but by interpretation of results and their plausibility which depends above all on the correctness of the reflections of the research worker. On a general level attention is paid to the description, comparison and evaluation of correlations, in particular the possibility to conclude from statistical correlation that a causal relationship exists. In the present as well as in previous articles the authors emphasize repeatedly that statistics are only one of the important tools of the doctor, but they cannot replace his responsibility, nor his professional experience.
- MeSH
- statistika jako téma * MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
The authors present two nonparametric tests which can be used to compare the level of a random variable based on two independent random samplings. Wilcoxon's (Mann-Whitney's) test is based on the sum of sequences which are appropriate for individual elements in a common group. In large samples the tested criterium is based on the normal distribution, for small samples a table of critical values is enclosed which makes rapid decision possible. The median test is based on the idea that if two independent random samples are from the same population both samples contain equal numbers of elements above and below the median for the common group of all elements of both sub-groups. The tested criterium to which the median test leads is the chi 2-test or Fisher's test of accurate probabilities.
- MeSH
- statistika jako téma metody MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- Klíčová slova
- HEALTH EDUCATION *, HEALTH SURVEYS *, STATISTICS *,
- MeSH
- biometrie * MeSH
- lidé MeSH
- statistika jako téma * MeSH
- zdravotní výchova * MeSH
- zdravotnické přehledy * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
This is the introductory article of a series of eight where the authors discuss non-parametric methods. They compare the advantages and disadvantages of non-parametric methods with parametric ones. Non-parametric methods can be used in particular where the investigated variables do not have a normal distribution, where the small size of the investigation and the type of classification do not permit to test, when information on the investigated variables are presented by means of rank or normal scales etc. Their disadvantage is a smaller ability to refute the null hypothesis, when it is not correct, as compared with parametric tests.
- MeSH
- statistika jako téma * MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
The authors deal with the evaluation of dependence between two quantitative variables. They analyze Spearman's and Kendall's rank correlation coefficients. The procedure is explained on examples. Decision taking between the zero and alternative hypothesis is made possible by the enclosed tables of critical values. When the number of data is higher than 30, the significance of the two coefficients can be evaluated by means of the testing characteristic with a normal distribution.
- MeSH
- statistika jako téma * MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
The authors present two non-parametric tests which are suitable for comparison of the level of a random variable on the basis of results obtained from two dependent samples. The sign test is discussed which is based on the evaluation of the statistical significance of the difference in the number of positive and negative deviations. The application of this test in practice is facilitated by the enclosed table which gives critical frequencies which still lead to the refusal of the zero hypothesis. The authors discuss also Wilcoxon's test for paired values. This test takes into account not only the trend of deviations but also their magnitude and thus uses more information than the sign test and has thus a greater scope. For this test an auxiliary table of critical values is also presented.
- MeSH
- statistika jako téma * MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
The authors mention two tests for comparison of the level of random variables in more than two random samples. It is thus a question of generalization of methods presented in parts II and III. Friedman's test resolves the position for dependent samples when data assembled during different experimental situations in the same group are to be evaluated. This test calls for a complete series of measurements from every statistical unit, in mathematical terminology this means that the samples are equally extensive. In case of large samples Friedman's test is based on chi 2 distribution; for a small number of samples special tables of critical values are given. Kruskal-Wallis's test resolves the position for independent samples. It is also based on chi 2 distribution.
- MeSH
- statistika jako téma * MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
The authors describe the procedure, suggested by Kendall for evaluation of the concordance of several sequences. Kendall's coefficient, called also coefficient of concordance, can be used when it is possible to assess the sequence of investigated variables. The calculation procedure and interpretation of the coefficient is explained on a simple example. For evaluation of significance tables of critical values are presented for 1% and 5% levels of significance.
- MeSH
- statistika jako téma * MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- MeSH
- krysa rodu Rattus MeSH
- počítače * MeSH
- regenerace jater * MeSH
- statistika jako téma * MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
