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Statistical analysis

Statistical analysis of data in Natural Sciences

Usually I collaborate performing the statistical analysis of data in research projects in biology. Almost all the problems that I have worked I used a mixture of methods of statistical inference, multivariate analysis, and methods of descriptive statistics.

  • The problems that I have worked with have been very different nature: physiology of fungi [1c, 2c], plant virology [4c], ecology of spiders [3c, 5c], populations of cells [6c], geology [7c], botany [8c, 9c], vascular system in mammals [10c], diagnosis of depression through the multivariate statistical analysis of laughter [11c, 12c].


  • An important issue is the analysis of data from computer simulation experiments in artificial life and artificial intelligence. Obviously these data differ from those obtained in experiments performed in nature or in the laboratory. Statistical analysis of data from simulation experiments requires some care: in [21] we reviewed some general protocols applied to evolutionary computation experiments.


A book about statistical methods in behavioral biology

In 1995 I wrote in collaboration with specialists in animal behavior the book entitled Statistical Methods in Behavioral Biology (Transl:. In spanish, Métodos Estadísticos en Biología del Comportamiento).

The book, eminently practical, deals with a simple and direct language, the theoretical foundation and application of statistical techniques in the field of Behavioral Biology, whether animal or human. The book is primarily aimed at students from Psychology, Biology, Medicine and, in general, all those who are interested in the statistical analysis. The book contains many examples that have been taken from these disciplines, to show the use of statistical methods. As innovation is noteworthy that is the first book in spanish incorporating a 'floppy disk' with the programs for the statistical tests described therein, and is the first to describe circular statistics techniques, useful in the study of animal orientation and biological rhythms.

The book is accompanied by 'PhiStat 1.0' program: a collection of programs in Turbo Pascal (MS-DOS). The program includes different techniques ranging from classical statistical tests (ANOVA, chi-square test, ANOVA and regression analysis, etc.) to circular statistics techniques (periodic regression, Hotelling test, the cosinor method, etc.). It also includes 'Dr Hypo' , a tool for interactive solving hypothesis testing and various utilities (T-test for paired observations, etc.) as well as routines for producing statistical tables (Z, F Fisher T-student, chi-square, etc.).

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 R. Lahoz-Beltra, J. Ortega, C. Fernández-Montraveta. 1995. Métodos Estadísticos en Biología del Comportamiento. Editorial Complutense (ISBN  84-7491-512-0), pp 1-232.


Statistical analysis of laughter and diagnosis of depression


There are no studies in psychiatry attempting the use of laughter as a diagnostic tool. In the present study [11c, 12c] we extracted nine temporal and acoustic variables from laughter episodes, looking for establishing better pattern-classification methods. These variables are number of bouts, voiced percentage, bout duration, mean energy, mean entropy, standard deviation of fundamental frequency, jitter, shimmer and harmonic to noise ratio. A library of records of laughter episodes was created and the values of the previous variables were statistically analyzed. We found that laughter may be applied as a diagnostic tool in the onset and evolution of depression and, potentially, of neuropsychiatric pathologies [READ MORE].



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