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to other cities with weekly collection. Not all of the residents may have been aware of weekly pickup because approximately 20% of the Weekly area residents put their material out every other wcek. Participation . "Before" period. The strongest participation rates in the "Before" period were in the two most affluent areas, the Single-Stream Contrast area at 91 % and the Control area at 85%. The other areas were grouped between 78% and 82%. . "During" period. In the "During" period the Contrast area retained the highest participation rate at 94% followed by the Two Bin area at 91 %, with the other areas grouped between about 86% and 88%. . Change. The largest change in participation rate was in the Two Bin area, where the participation rate rose by about 13%, while the increase for the other areas r"llged from about 2% t07%. The participation rate for the Control area increased the least, by only 2%;no significant change would be expected in a Control area, and this change is relatively small. Material Composition Sorts and Analysis To compare the types and quantities of recyclable and nOll-t"rgeted m~terials collected in each ofthe various pilot study areas, the pilot program included detailed materiaLcomposition sorts and analysis. As shown in Appendix A, BecklKrivit developed the composition analysis categories, the materials composition protocol, data sheets, and health and safety plan, and provided the statistical analysis. The protocol incorporated American Society of Testing and Material (ASTM)E;tandards. One sort was conducted in the two-month "Before"period(J\ll1e-J~ly 2004) and two were conducted in the four-month "During" period (August-November 2004LThe number of sorts was a balance between having sufficient samples for statistical analysis and available staff time and other resources. Using the BecklKrivit protocol, City staff coordinategthe comp()~ition sorts, wllich were conducted at the City public works garage by City staff and waste and recycling professionals from t~emetropolitan area. For each sample nine categories of recyclable and four c<l\egoriesofnon-targeted materials were sorted and weighed. The data from th9sorting evellts)Yere ellt9red into R. W. Beck's specially designed statistical model, which uses 90% con~?eBce intervals t6M9asure st~tf~tically significant differences (see the analysis in Appendix A for a further explall~tion of statistic~lissues).In some cases, data from the pilot areas were aggregated to increase the numbero~:~amples for st~tistical analysis: thus, in parts of the analysis data for both the Single- Stream and Single-Stream Contrast areas were aggregated and compared with the aggregated data for all the dual-stream areas. Analysis The statistical analysis had two broad components, measuring ifthere was a statistically significant change in pilot areas in the percentages of different recyclable materials, and measuring if there was a statistically significant change in the actual weight of certain materials. The following is a summary of key findings from the Beck/Krivit analysis in Appendix D, which includes numerous comparison tables. Single-Stream The following were statistically significant: 18