Tham khảo tài liệu 'environmental management in practice part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The Statistical Distributions of Industrial Wastes an Analysis of theJapanese Establishment Linked Input-output Data 321 rate W We find that six out of seven wastes show the same statistical characteristics 1 the median is smaller than the mean and 2 the distributions have a long tail. But iron-steel slag 193 observations has a nearly symmetric distribution as shown in Figure 4a. According to the central limit theorem the distribution of a sample mean with a finite variance converges to the normal distribution. But our statistical test of the goodness of fit does not support gamma or normal distributions. The convergence in distribution to the normal distribution is not seen for distributions of other wastes either as shown in Figure 4b. The distribution for a positive random variable becomes exponential at the maximum entropy in the present case a statistical test rejects the exponential distribution also. 5 Median 95 Mean Inorganic sludge Sludge of polishing sand Waste plastics Waste paper Scrap iron Scrap glass Iron-steel slag Table 3. Simulated confidence intervals and the mean for unit waste generation rate W x Results for the distributions of the recycling rate using the same procedure as before are given in Table 4 and Figures 5a and 5b. Compared to distributions for the waste generation rates distributions for the recycling rates are nearly symmetric. And the figures are clearly different from those given in Figure 2 for population the distributions histograms of the waste generation rate. This difference arises because in case of distributions for recycling rates there is the effect of aggregation of recycling rates. The sample mean is almost the same .
