.. _sect_sensitivity: Normalized Sensitivity ====================== In addition to saving a :Ref:`sect_resistivity_file` for each inversion iteration, MARE2DEM will save a ``..sensistivity`` file that has the normalized data sensitivity computed by summing the Jacobian matrix columnwise over all *n* data: .. math :: S_j = \frac{1}{A_j} \sum_i^n | W_{ii} J_{ij} | where .. math :: J_{ij} = \frac{\partial d_i}{\partial m_j}, :math:`W_{ii}` is the inverse standard error for the *i*\ th datum, and :math:`A_j` is the area of the *j*\ th free parameter. The normalization by the parameter area decouples the sensitivity from the size of each parameter. Normalize *S* has units log10(S/m)/m\ :sup:`2`. The sensitivity can be used as a relative measure of data sensitivity to structure, but be aware this is a linearized approximation for what is a non-linear inverse problem, so sensitivity plots should be taken with a grain of salt.