| Variable | Describe | Note |
| WTP | Willingness to pay of HH | Yes = 1 No = 0 |
| Age | Age of head of HH | Continuous variable |
| Gender | Gender of head of HH | Male = 1 Female = 0 |
| Edu | Education level of head of HH | Under high school = 1 High school = 2 Collge = 3 University/ above university = 4 |
| HH size | Size of HH | Continuous variable |
| HH type | Type of HH | handicraft producers = 1 agricultural HH = 0 |
| HHapro | Access to media on environmental pollution | Many times = 1 Sometimes = 2 never heard of it = 3 |
| HH trade-off | Trade-off between economic development and the environment | Agree = 1 Disagree = 0 |
| Income | Income of HH | <10 million VND/month = 1 10 - 20 million VND/month = 2 21 - 30 million VND/month = 3 31 - 40 million VND/month = 4 41 - 50 million VND/month = 5 >51 million VND/month = 6 |
| Village | Village | KhacNiem (very far to polluted rivers ) = 1 Yen Phu (far to polluted rivers) = 2 Dai Bai (nomal to polluted rivers) = 3 Da Hoi (near to polluted rivers) = 4 PhongKhe (very near to polluted rivers) = 5 |
| WaS | Water source HH using | Use tap water = 1 Do not use tap water = 0 |
| BID1 | The first bid | Continuous variable |
| BID2 | The second bid | Continuous variable |