EDMOND DEMOLLARI1*, ETLEVA JOJIC1, VALDETE VORPSI1, ERTA DODONA1, ENKELEIDA SALLAKU2
1Department of Plant Sciences and Technologies, Agriculture University of Tirana, Tirana, Albania
2Department of Animal Production, Agricultural University of Tirana, Tirana, Albania
*Corresponding author e-mail: firstname.lastname@example.org
The main objective of the study was to compare in couple the produced biogas data groups in percentage per volume (%/vol.), through statistical analysis, obtained from different conditions and temperatures. Main methods applied were t-test, Fisher test (F) and Analysis of Variance (ANOVA). The substratum included in the study were: Inoculum with Concentrated feed. The comparison of variance of biogas data groups obtained for different temperatures (25°C, 37°C, 50°C) was initially performed using the Fisher test (F) by comparing Fcalc. with the Ftheore. that means at the given table, determined depending on the number of degrees of freedom (f1 and f2). Analysis of Variance (ANOVA) applied when the number of observations was greater than three at three temperature levels. The t-test was used to compare the averages of two independent biogas data groups generated with the same substrate but at three different temperatures as well as for different development conditions. Determination of Limit Differences (LD) with security levels 5%, 1%, and 0,1% became a precedent for comparing differences between averages, in order to determine it: essential, most essential, and very essential. From the t-test, it turned out that the calculated value of 10,721 was greater than the critical 1,977 and P < 0,05. By comparison, it was noted that for the same substratum and the same application temperature of 50°C, changing the experimental conditions (laboratory-environment), led to the essential difference in biogas generation. The conditions under which the experiments were conducted, were determinative of the amount of biogas produced.
Keywords: Analysis of Variances, t-Test, substratum, Fisher test (F)