Agilent Technologies NovoCyte Quanteon Operator's Manual page 36

Introduction
For example, Figure 8 shows FITC emission appears primarily in the FITC detector,
but a small portion of its fluorescence spills over into the PE detector. The spillover
is corrected by compensation, as indicated by the arrow in Figure 9. The purpose
of the compensation is to move the FITC-positive population downwards until it
has the same Mean or Median value of PE signal as the unstained population
(Figure 10).
Figure 9. Theoretical Display of FITC vs. PE without Compensation
Figure 10. FITC Spillover Optimally Compensated out of the PE Signal
Once fluorescence compensation has been set using compensation control
samples, such compensation settings remain valid for any subsequent sample,
because compensation subtracts a percentage of the fluorescence signal,
independent of the overall fluorescence intensity. Figure 11 illustrates this
36 NovoCyte Quanteon Flow Cytometer Operator's Guide