|
|
|
| The most important question in |
||
| epidemiology |
||
|
|
|
|
|
|
|
|
| • | Compared
to what? |
||||||
| • | Participants
to refusers |
||||||
| • | Cases
to controls |
||||||
| • | Exposed
to unexposed |
||||||
| • | Subjects
recruited/interviewed by one |
||||||
| method
to subjects recruited/interviewed by |
|||||||
| another method |
|||||||