| Variable | Description | Unit of Measurement | Expected effect |
| Dependent variable | |||
| OOP payments (Y) | The burden of OOP payments as a proportion of the total healthcare expenditures | Percentage (%) | + |
| Independent variables | |||
| The burden of untreated morbidity (X1) | Status of the presence of untreated morbidity in the household | Dummy: (1 if present; 0 if otherwise) | ± |
| Medical check-ups limitations (X2) | Affordability to meet medical check-ups charges | Dummy: (1 if affording; 0 if otherwise) | ± |
| limitations to cover costs of treatments (X3) | Affordability to meet costs of treatments | Dummy: (1 if affording; 0 if otherwise) | ± |