Table 1. A simple illustrative hypothetic example on the effect of global expression shift.

Experiment	#1		#2
Group	Control	Test	Control	Test
Shift factor	1.0	2.0	1.0	2.0
The number of cell	2000	1000	2000	2000
Expression of gene A	XA	0.5YA	XA	YA
Expression of gene B	XB	0.5YB	XB	YB
Test-control ratio of gene A	0.5YA/XA		YA/XA
Test-control ratio of gene B	0.5YB/XB		YB/XB