Abstract

Statistical tests were carried out in order to assess the possibility of the embedding of mineral constituents enhanced by the alkaline pH of 8.8 in the mass of the paper, and to investigate if they influenced the physical characteristic of Bekk smoothness of the paper sample. For the comparison of the means, of the two sides of paper Bekk smoothness, we used one-way ANOVA. The p-value of ANOVA p=0.005<0.05 showed statistically significant differences between the Bekk smoothness of the two sides of the paper. In the descriptives table, the positive skewness values of +0.365 and +0.233 for each of the two sides, indicated a tail to the right of the normal distribution of our data. The kurtosis value of -0.358, and -0.601 indicated that the normal distribution tended to be flat. The table of percentiles produced the weighted average and the 5%, 10%, 25%, 50% and 75% percentiles for the variable Bekk smoothness. In the extreme values table, we tried to identify outliers and the extreme values that caused the skewness of the distribution. Next, we compared the means of the smoothness Bekk of the two sides of the paper, with the residue on ignition at 900oC value, and the pH value of the sample. Post hoc tests, in a multiple comparison table, indicated that there was a significant difference at the 5% level of significance between Bekk smoothness mean value, and the mean of the ash content value, and the pH value. A homogeneous subset table indicated that the groups of the pH value, and the ash on ignition at 900 °C value were significantly different from the groups of the Bekk smoothness sides A, and B of the A4 copy paper.

Keywords: Bekk smoothness; Ash on ignition content; pH value; Compare means; One-way ANOVA; Descriptives table; Post hoc tests