The measurements for Fig. \ref{fig:MethodTwoGraph} were determined using a constant polarizer angle of \(\frac{\pi}{4}\) because that is the point when we have a maximum sensitivity. When we stay at a constant angle, that would be equivalent to taking the derivative at a point in Fig \ref{fig:MethodOneGraph}. Therefore, it makes sense to have a linear fit, refer to Fig. \ref{fig:MethodTwoGraph}.