These studies often rely on community- or household-level data using probit or tobit models to estimate the frequency of recycling as a function of different policy instruments and household attributes (e.g. income level, value of time, education, and number of persons in the household, age, renting or ownership). Most studies that are presented here are from the 1990s and the 2000s. The field experiment covered several voluntary recycling programs (treatments) which differ when it comes to convenience factors such as sorting requirements, frequency and location of recyclable collection as well as the amount of recycling information.