Statistical methods are necessary to obtain a reliable measure of a given effect.
Typically, researchers report their findings by listing those regions which show significant statistical activity in a group of subjects under some experimental condition or task. A number of methods create statistical parametric maps of the brain on a voxel-basis. Other researchers have turned to computing the statistics not on individual voxels but on anatomical regions. The correlation coefficient is then used to quantify similarity in response for various regions during an experimental setting. The functional inter-relationships can become rather complex and are best understood in the context of the underlying 3D brain anatomy.