Table 2

Definition of the categories used for classifying cross sectional studies

Category Definition (according to the criteria listed in table 1)
4Criteria (a–e) are all met.
3Criteria (a, b, andd) are met; criteria (c or e, or both) are only partly met
2(a) Exposure assessment at least qualitatively—for example, job name only
(b) Criterion (b) is met
(d) Only one or two of the four most important confounding factors considered
(c and e) These criteria may or may not be met
1Still less comprehensive than category 2