Figure 4.

Predictive strength of anticipatory activity: unbiased estimates using LASSO-PCR. A, Predictive accuracy obtained from LASSO-PCR within an a priori cortical mask for studies 1 (blue) and 2 (red). The scatter plot shows observed placebo-analgesia scores (y-axis) versus predicted by the cross-validated analyses (x-axis). The accuracy estimate is minimally biased; the cross-validation scheme is known to slightly underestimate predictive accuracy. B, Minimally biased predictions from LASSO-PCR for study 2 alone. Predictive accuracy was substantially stronger for study 2.