Method used to determine the resolution of the map. The first of the two fundamentally different methods is one that relies on dividing the the data into two halves and then calculating two independent reconstructions which are then compared by Fourier Shell Correlation (FSC) or differential phase residual (DPR). The second different method of assessing resolution is more relevant where there is a combination of EM and X-ray data. The similarity between the EM density and the electron density corresponding to the atomic structure can be used to determine the resolution of the EM map.