Paper detail

Selective Correlations - the conditional estimators

The problem of Voodoo correlations is recognized in neuroimaging as the problem of estimating quantities of interest from the same data that was used to select them as interesting. In statistical terminology, the problem of inference following selection from the same data is that of selective inference. Motivated by the unwelcome side-effects of the recommended remedy- splitting the data. A method for constructing confidence intervals based on the correct post-selection distribution of the observations has been suggested recently. We utilize a similar approach in order to provide point estimates that account for a large part of the selection bias. We show via extensive simulations that the proposed estimator has favorable properties, namely, that it is likely to reduce estimation bias and the mean squared error compared to the direct estimator without sacrificing power to detect non-zero correlation as in the case of the data splitting approach. We show that both point estimates and confidence intervals are needed in order to get a full assessment of the uncertainty in the point estimates as both are integrated into the Confidence Calibration Plots proposed recently. The computation of the estimators is implemented in an accompanying software package.