Table 3. Influence of variation in cDNA input (±20%) of control and sample (high and low level) on the variation in relative expression ratio based on equation 1 and the error of mathematical model, expressed as CV of R.

Gst	TyrA	PyrB
E = 1.99	E = 2.09	E = 2.16
High cDNA input level	ΔCP = +5.283	ΔCP = –4.311
80% cDNA input ΔCP = –0.277	R = 59.476	R = 0.04375
100% cDNA input ΔCP = –0.256	R = 58.625	R = 0.04312
120% cDNA input ΔCP = –0.227	R = 57.459	R = 0.04226
Mean of R	58.45900	0.04304
Error/CV of R	1.73%	1.74%
Low cDNA input level	ΔCP = +5.487	ΔCP = –4.277
16% cDNA input ΔCP = –0.050	R = 59.104	R = 0.03844
20% cDNA input ΔCP = –0.127	R = 62.102	R = 0.04031
24% cDNA input DCP = –0.077	R = 60.208	R = 0.03914
Mean of R	60.471	0.03930
Error/CV of R	2.50%	2.49%