Table 5.

The Code Book.

Level 1	Level 2
Selection	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance
Confounding	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance
Performance	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance
Attrition	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance
Detection	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance
Analysis	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance
Reporting	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance
Early termination	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance
[ad hoc codes]	Before exposure
	During exposure
	After exposure
	Higher relevance
	Lower relevance