Table 4

Principal strata for both compliance and pregnancy as IOs
Treatment assigned Sample space of final outcome: preeclampsia
Control Treatment
Principal strata Treatment Pregnant (0 = placebo; 1 = calcium) Treament received (0 = no; 1 = yes) Pregnant (0 = no; 1 = yes) Labels Assigned to control Assigned treatment Proportion in the stratum (Average treatment assigned ) Effect
1 0 0 0 0 Never-takers never pregnant * * p1 *
2 0 0 0 1 Never-takers pregnant under treatment * (no, yes) p2 *
3 0 0 1 0 Compliers never-pregnant * * p3 *
4 0 1 0 0 Never-takers pregnant under control (no, yes) * p4 *
5 1 0 0 0 Defiers never-pregnant * * 0 *
6 0 0 1 1 Compliers pregnant under treatment * (no, yes) p6 *
7 0 1 0 1 Never-takers always-pregnant (no, yes) (no, yes) p7 0
8 1 0 0 1 Defiers pregnant under treatment * (no, yes) 0 *
9 0 1 1 0 Compliers pregnant under control (no, yes) * p9 *
10 1 0 1 0 Always-takers never-pregnant * * p10 *
11 1 1 0 0 Defiers pregnant under control (no, yes) * 0 *
12 0 1 1 1 Compliers always-pregnant (no, yes) (no, yes) p12 τ12
13 1 0 1 1 Always-takers pregnant under treatment * (no, yes) p13 *
14 1 1 0 1 Defiers always-pregnant (no, yes) (no, yes) 0 τ14
15 1 1 1 0 Always-takers pregnant under control (no, yes) * p15 *
16 1 1 1 1 Always-takers always-pregnant (no, yes) (no, yes) p16 0

*Final outcome or effect not defined; **it is possible in theory to have always-takers, because women can take calcium supplementation out of the trial intervention.

Seuc et al.

Seuc et al. Trials 2013 14:78   doi:10.1186/1745-6215-14-78

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