more focused on the benefits of introducing new SWM approaches, such as kerbside/dropoff recycling, composting and incineration, which aim to reduce landfill. But most of the developing-country-based CV studies are focused on the benefits of providing/improving the basic or traditional solid waste disposal methods such as collection, transportation and landfills with better pollution control measures.

With regard to the survey methods used, while in-person, mail and telephone surveys have been used in almost equal frequencies in the developed-country studies, the in-person surveys dominate in the studies conducted in the developing countries. The value elicitation format that is used most frequently is the one/two-step dichotomous choice questions,<sup>7</sup> even though we also find a few studies using open-ended questions (Sterner and Bartelings, 1999; Bluffstone and Deshazo, 2003; Osumanu, 2009) and payment cards (Aadland and Caplan, 1999; Ichoku et al. 2009).

The WTP estimation results of the previous studies provide some interesting and common findings. In general, people in both developed and developing countries are willing to pay for SWM programs, and the requirements for improvement in SWM services are very often placed ahead of other major social concerns such as improvements in water and sewer services, housing, indoor air pollution and insect pests, etc. (Altaf and Deshazo, 1996; Othman, 2002; Osumanu, 2007). The WTP value increases in general with household income (Altaf and Deshazo, 1996; Lake et al., 1996; Aadland and Caplan, 1999; Othman, 2002; Huang and Ho, 2005; Palatnik and al., 2005; Fonta et al., 2007; Osumanu, 2007; Afroz et al., 2009 and Ichoku et al. 2009), respondent’s education level (Altaf and Deshazo, 1996; Aadland and Caplan, 1999; Huang and Ho, 2005), conscience about the seriousness of solidwaste-related pollution problems (Huang and Ho, 2005, Ichoku et al., 2009), past positive experience in receiving the SWM services and trust in the proposed project (Afroz et al. 2009). This suggests that SWM service is a normal economic good. Female respondents have a general tendency to be willing to pay more than the male respondents (Aadland and Caplan, 1999; Fonta et al., 2007; Ichoku et al., 2009) Family size seems to affect negatively the WTP (Huang and Ho, 2005) but the families having kids may be ready to pay more (Lake et al. 1997). This finding in fact echoes to the conclusion of Johnstone and labonne (2004). Based on an OECD-country macroeconomic database, they found the family size does not affect significantly the demand for SWM, since the children and adults apparently do not play the same role in the determination.

Several studies, especially those conducted in the developing countries, also reveal an important phenomenon that although people rank improper solid waste disposal as the top environmental problem, the user fee that they are willing to pay can only partially cover the cost of the service. Bluffstone and Deshazo (2003) concluded that the WTP for upgraded landfills covers only about 80-90% of the cost for a project in Lithuania to upgrade their SWM system to European level. Naz and Naz (2005) found the ratio of WTP over the total cost to be only 22-35% in the Philippines. Palatnik et al. (2006) also mentioned the necessity of subsidy to achieve an efficient level of recycling for the case of Israel.

Table 1 lists the WTP values reported in various CV studies. Although the components of the hypothetically proposed projects are different from each other, a general impression is that the WTP for SWM service does not occupy an important share in household income. In general,

> 7 Examples include Altaf and Deshazo (1996), Lake et al. (1996), Othman (2002), Tiller et al. (1997), Naz and Naz (2005), Palantnik et al. (2005), Basil et al. (2006), Jin et al. (2006), Lal and Takau (2006), Fonta and al. (2007), and Afroz et al. (2009).

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