Watson, Chambers, & Smith: A Pragmatic Approach to the Analysis of DNA Histograms with a Definable G1 Peak [Cytometry 8:1-8 (1987)]

Fox: A Model for the Computer Analysis of Synchronous DNA Distributions Obtained by Flow Cytometry [Cytometry 1:71-80 (1980)]

Unfortunately, no algorithms are consistently reliable in fitting all the distributions you may encounter. You may have to experiment with different options and fitted curves to find your best results.

You should first apply the model of choice to the data and view the calculated statistics. For most distributions, FlowJo will be able to locate the G1 and G2 peaks, and thereby accurately fit the distribution with the model. (Of course, some distributions are not easily fit by some of the models; you may have to select an alternative model or edit the curves to obtain a better fit).

When you encounter a difficult-to-fit distribution, you may want to manually edit the curves. After choosing 'Edit Model Curves', the G1 and G2 curves are labeled and drawn with vertical lines. You may select an individual curve and begin dragging the curve (with the mouse button pressed) to obtain the desired position and shape of the curve. When the mouse is released, the statistics are recalculated to show you if the fit has improved.

There are three ways to edit a curve:

If you drag the vertical line associated with a curve, you can modify the position of the mean along the x axis by moving the mouse left or right and you can modify the standard deviation of the curve by moving the mouse up or down (moving up increases the standard deviation, moving down decreases it). The amplitude of the curve is automatically fixed to the value of the parameter's histogram data.

If you drag the topmost 'handle' of a selected curve, you can modify the position of the mean along the x axis and the value of the amplitude along the y axis.

If you drag the left or right 'handle' at the bottom of a selected curve, you can modify the standard deviation value.

With a little practice, you will find that you can edit the curves to achieve a smaller RMS value.