Why is the limit for a sample passing or failing the quality control set to +/- 0.3NPX of the plate median for Incubation control 2 and the detection control?

To set this cut-off, Olink has analyzed 2000 EDTA-plasma samples, and the results showed that 99.7% of all samples ended up between these limits for our internal controls.

We could also see that samples that deviated by more than +/- 0.3 NPX showed differences that affected data quality.

0.3 NPX equals a CV of 15%, so in other words, samples can differ by 30% from each other and still pass the quality control.