Mathematics in Education, Research and Applications (MERAA), 2020(6), 2
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Published online 2020-12-30
DOI:https://doi.org/10.15414/meraa.2020.06.02.54-63
Regression analysis of expanded polystyrene properties
Dušan Páleš, Milada Balková
Slovak University of Agriculture in Nitra, Nitra, Slovak Republic
Article Fulltext (PDF), pp. 54–63
- Own measurements examine the tensile strength of expanded polystyrene (EPS) depending on its bulk density. 30 samples were used to calculate the correlation coefficients between these two properties. In addition to the
standard Pearson coefficient, we also calculate the rank correlation coefficients, Spearman´s and Kendall´s. By testing the hypotheses, we verify the correlation of the entire population. After finding a relatively close
correlation (0.6 - 0.8), we apply different regression models, especially polynomial, but also exponential. We evaluate the properties of parameters in models, their point estimates and confidence intervals. Based on the
characteristics of each of the seven regressions, we found the best exponential form of the dependence, before the linear polynomial. The complexity of a mathematical model does not always mean that it is also a more
accurate approximation. On the other hand, a simple model makes it possible, in addition to its ease of use, to more closely reflect the examined dependence.
- Keywords: Expanded polystyrene (EPS), bulk density, tensile strength, correlation, regression model
- JEL Classification: C12, C13, C15