In order to interpret variations in the electrical properties, and create a ground modal, it is necessary to mathematically calculate the subsurface conditions required to produce an equivalent dataset to the one recorded by the instrument- this is called inversion. The recorded Apparent Resistivity is represented as a point measurement in the dataset. As a result the each resistivity measurement represents the bulk resistive properties of the ground- referred to as the Apparent Resistivity.
Resistivity measurements rely on expanding the electrode separation in order to achieve ever deeper measurements, leading to a larger volume of the subsurface material being sampled for each successive depth level.
