User manual

94 | Droplet Digital
™
PCR Applications Guide
Appendix B
Technical Error Bars
in Droplet Digital
™
PCR
Because Droplet Digital PCR (ddPCR
™
) is a digital counting system, you can calculate the
measurement error based on the droplet data from a single well. This is the technical error
(also referred to as the Poisson error in QuantaSoft
™
software), and it is a good estimate of
the errors you can expect to see on true technical replicates (defined as aliquots of the same
starting material loaded into multiple ddPCR wells).
The technical error can be calculated from the data points obtained from a single well or
multiple wells merged together. For a good assay, the technical error will be approximately
equal to the standard error of the mean.
Conceptually, there are two contributions to the error bars: subsampling and partitioning.
Subsampling
In most molecular biology experiments, we analyze part of a whole (a subsample).
Examples include:
■
Blood sample
■
Tumor biopsy
■
Aliquot from a tube of DNA