ZLI Data Analysis: Understanding the Variables
Diversion rate is the main variable for the ZLI data analysis. Diversion rate formula: diversion rate= (recycling/total of waste and recycling). Recycling figures are reported values (exogenous variable). Total waste and recycling for individual categories (in the years 2016-20[1]) is determined by its’ % share of the constant figure of total of all categories from the total waste and recycling figure. The constant figure of the Total of All Categories total waste and recycling is determined by taking the sum of all individual categories recycling plus the reported aggregate figures for landfill(waste)(exogenous variable). For individual categories(2016-20), total waste and recycling(endogenous variable) is determined by taking the same % share of the total waste and recycling set by the baseline year(2015)[2]. This % share of the total waste and recycling is held constant for all categories going forward. The difference between the reported recycling figures and those determined by the constant total waste and recycling figure gives an estimated landfill value(endogenous variable) for individual categories.
This can be problematic going forward because the categories which are held at a constant % of total can have an individual recycling value with a larger share then the individual categories total waste and recycling value. This requires that the landfill value represent a negative value to bring the total to its constant % of the total. Logically, negative landfill numbers make no sense. This is also where diversion rate can exceed 100% which is also not logical. It is most likely true that the % share of total waste and recycling changes for the individual categories year to year but without the ability to determine the individual categories landfill values year to year, the actual total waste and recycling for these categories can’t be determined. This is the main limiting factor of the analysis.