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“Perfiles” (ISSN printed 1390-5740 - Electronic ISSN 2477-9105) is a scientific research journal published by the Science Faculty of “Escuela Superior Politécnica de Chimborazo” (Riobamba, Ecuador). It is being published following a biannual periodicity [(January - June) and (July- December)]. Its mission is to disseminate scientific-technological information related to predominant knowledge areas and related branches studied in the institution.

The main objective of the journal is the publication of original or review articles, short communications, technical reports, standards, specifications, letters to the editor, communications to congresses and, in short, other contents which are relevant to the scientific community.

“Perfiles” is a free access research journal. Its online version is available at the web address:
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  • Physical
  • Math
  • Chemistry
  • Biological Sciences
  • Health Sciences
  • Alternative energies

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Issue Nº 23 Vol.1 - [January - June 2020]


AUTHORS: Natalia Alexandra Pérez, Héctor Salomón Mullo, Jessica Alexandra Marcatoma

The purpose of this research is to demonstrate the existence of climate change in a high Andean ecosystem of Ecuador, through the study of the linear trend of the maximum, minimum, average and precipitation temperature of the meteorological station (M1036) of the National Institute of Meteorology and Hydrology (INAMHI) located in the Higher Polytechnic School of Chimborazo (ESPOCH). The univariate statistical analysis of the multiyear monthly averages of the years 1976 to 2017 determined a dry climate in the months of June to September and a humid climate in two intervals (February - May and October - December). On the other hand, by means of the Mann Kendall Test, it was evidenced that the average temperature showed a decreasing tendency (-0.004); while the maximum, minimum and precipitation temperature had an increasing tendency (0.0002, 0.003, and 0.039 respectively), where the last two are significant at 5%. It is concluded that climate change is plausible in the central andean area of Ecuador, generating environmental problems that we must face, and that public policy articulators in the country should consider as inputs for planning.
Keywords: Linear Algebra, Vector Space, Change of basis, MATLAB


Issue Nº 24 Vol.1 - [July - December 2020]


AUTHORS: Pablo Flores Muñoz, Laura Muñoz Escobar, Geoconda Velasco Castelo

Previous studies reveal that samples with outliers alter the type I and type II error of a t-Student test for inference of a mean. The methodology that these works use to simulate extreme data consists of mixing two different normal in order to contaminate the data. We think that this technique is not the most appropriate, since, when making this process, the result is not a new normal, which is breaching the main assumption of the test. In this work, this methodology is repeated in order to verify the problems described, but atypical data are also generated from a single normal without the need for any contamination. Using this last methodology, and with a stochastic simulation process, the probability of type I and type II error is estimated, from which it is concluded that the t-Student is a robust test against the presence of outliers and its power does not depend of the number of extreme data generated in the sample.
Keywords: outliers, t-Student, mean, inference


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