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Table 2 Principal strata according to potential behavior in each source of noncompliance (alternative version of Table 1 )

From: Intermediate outcomes in randomized clinical trials: an introduction

Strata

Behavior pattern in noncompliance sources 1, 2 and 3a

Treatment assigned and received for subject R in corresponding stratum

Compliers

Yes, no, no

Ri(Ti) = Ti

 

Yes, yes, no

 
 

Yes, yes, yes

 
 

Yes, no, yes

 

Always takers

No, yes, no

Ri(Ti) = 1

 

No, yes, yes

 
 

No, no, yes

 

Never-takers

No, no, no

Ri(Ti) = 0

Defiers*

  
  1. *As the trial is blinded, there are no defiers, as subjects cannot systematically take the opposite treatment; **Ri = treatment received, Ti = treatment assigned (0 = placebo, 1 = calcium); asources of (non)compliance: 1, taking >80% of pills assigned; 2, collateral treatment involving substantial calcium indicated by physician; 3, self-indicated collateral treatment involving substantial calcium.
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ISSN: 1745-6215