In technological contexts field-emission data are often plotted using (a particular definition of) F M or 1/ F M as the x -coordinate. However, for scientific analysis it usually better not to pre-manipulate the experimental data, but to plot the raw measured i - V data directly. Values of technological parameters such as (the various forms of) γ can then be obtained from the fitted parameters of the i - V data plot (see below), using the relevant definitions.