| Value |
Category |
| 0 |
No treatment or cleaning |
| 1 |
Cloth |
| 2 |
Candle filter |
| 3 |
Advanced filter |
| 4 |
Boil |
| 5 |
Chemical |
| Sysmiss |
|
Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.