Time series analysis of the effects of refuse collection on recycling: Taiwan’s “Keep Trash Off the Ground” measure

The state of recycling in Taiwan has seen significant achievements due to various recycling policies implemented by environmental agencies in recent years. These policies include the “Keep Trash Off the Ground” (KTOG) measure, the “Four-in-One Recycling Plan”, the per-bag trash collection fee and mandatory garbage sorting. An important question worthy of study is which of these policies has had a more pervasive and critical impact on the outcome of recycling. For example, there is evidence that the KTOG measure made it more convenient for people to begin recycling. This study therefore first analyzed the monthly data over the past decade on the amounts of recyclables in Taiwan’s three major cities. By examining time series plots and employing an analysis of the time series intervention model, we can better understand the extent of the effects of the KTOG measure on these cities’ amounts of recyclables. The same effects were also analyzed for the mandatory garbage sorting policy and the per-bag trash collection fee. Results show that the KTOG measure, essentially a change in refuse collection practice, presented consistent and significant effects on these cities’ amounts of recyclables. It is suggested that the key to improving participation in a recycling program in waste management is for techniques to be tailored to actual settings in a way that facilitates citizen cooperation.