2005 Recycling Pilot Program Report

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March 23, 2005 Page 4 Number of Tab1e 3 City of Roseville lVumber of Samples Sorted Number of Dual Total Average Single Total Average Stream , Pounds Pounds per Stream Pounds Pounds Samples Sorted Sample Samples Sorted per Sample Seiore Pilot 22 4,708 214 - - - During Pilot 26 7,105 273 8 2,2fi9 284 Data Collection Data sheets were completed during the sampling and sorting of the recyclable materials. The tare �veight of the container, and the weight of the individual xnaterials plus the tare weight, were recorded on the data sbeets by the sort crew supervisor. The data sheets used in 1he siady can be found in Attachment C. Stat�stical Modeling The data from the sorting events were entered into R_ W. Becl�s specially designed statistical model (Model). The Model has been developed in Microsoft Excel for easy accessibility and use. The Model statistically manipulates the data to calculate the mean, 90% confidez�ce intervals, and stanciard deviation for individual maierial categories. In addition, the Model is structured to identify where specific samples could be considered statistical outliezs. The mean represents the mathematical average or average percent of m.aterial composing the recyclable materials stream. The confidence inierval is an expression of accuracy. It provides the upper and lower lixnits of the actuai mean for all the recyclables in each sample, based on the sorting and sarnpling of #he materials. For example, the 90% canfidence interval represents that tbere is a 90% level of confidence that the trae population mean falls within the upper and lower bounds af the confidence intereal. The 90°/u confidence interval is the generally accepted standard by the industry for solid vvaste ar�d recyclable matezials composition studies. In general, the more samples that are sorted, the narrower the con�den.ce interval. The narrower the intervals, the less variability in the data. We believc it is critical when comparing the recyc�able materials co3mposition results that tlie confidence intervals are considered along with tlae mean percenta�es. �n addition, the total quanti#ies of rnaterials collected for each route were compiled during the sorting and sarnpling pzocess. This data was analyzed separately to identify the mean quantities collected v�ith the various collection mcthods and the applicable standard devia�ions. O1-00253-1U I OI-0101 � 070001 [ 13500 P:113500 Ramsey Co. 2003�RTA1Roaeville\FA1B i544 - Final Data Analysis