Azure Cielo Real-Time PCR Systems User Manual
Page 41
Can I compare data that I have obtained from a different instrument to that which I have run on the
Cielo? And if so, how do I do that?
It is generally not permissible to directly compare data generated from two different instruments even if the
assay run is the same. Different instruments can have slight fluctuations in the temperatures within the block,
the ramp rate, threshold determinations, among other potential influential factors.
A calibrator sample could be run on both instruments which would allow some comparisons of data based on
that calibrator sample and its result obtained on both instruments.
Even if data has been generated on two different instruments, the final data analysis results could be
compared. For example, if an investigator was running a standard curve, and then determining a copy
number of a target, that result could be compared to a similar run on a different instrument for reproducibility.
What is the difference between the C
t
/C
q
calculations when using regression versus threshold-based?
Which one should I use?
The Cielo Instrument Software can determine C
t
/C
q
using either regression or threshold.
Regression will consider the individual amplification plots and their slopes to determine when that sample
has entered the exponential phase of PCR and the corresponding C
t
/C
q
. Efficiencies of the reactions can also
be determined without running a standard curve.
Threshold based C
t
/C
q
uses a threshold setting determined by the software which defines where background
signal ends and true signal emerges.