Clinical Trials

❘❙❚■ Chapter 30 | Missing DataFigure 3. Proportion of missing information by visit for different missing data scenarios.Panel A: Dataset IIPanel B: Dataset IIIPanel C: Dataset IV0.8Group AGroup B0.8Group AGroup B0.8Group AGroup B0.60.60.6Proportion0.40.40.40.20.20.20.00.00.01 2 3 4Visit1 2 3 4Visit1 2 3 4Visitgroups. These patterns of missing data can help us to understand the underlyingmechanisms of missing data in the analysis of real clinical trialsStatistical analysisEach of the four datasets was analyzed using three different methods:• analysis of all available data• analysis of complete cases only• LOCFThe model used in all the analyses was the same as that used in the generationof the full dataset, with the addition of interaction terms between visit andtreatment group so as to investigate potential interaction effects between visitand treatment caused by different missing schemes. Figure 4 presents the fittedmean responses by treatment group and visit, whilst Table 2 presents theestimated treatment effects (standard errors) at the final visit.348