Fig. 1From: Item response models for the longitudinal analysis of health-related quality of life in cancer clinical trialsRelationship between the CdF and the IRT parameterization for dichotomous items where F(η)=F(α j (θ−δ j )). a presents the different CdF for one item j given α j =1 and δ j =0. b presents the logistic CdF adjustment for three items (j=1,2,3) with different α j and δ j =0, given the linear predictor defined in Eq. (1)Back to article page