Figure 4.

Intra-assay variation by the NLR (model 4) and by the CT method. Real-time RT-PCR data for ACTB, IL18 and TNFA on RNA extracts from human gastric mucosa. Plots show intra-assay variation or error (difference between duplicate values) vs. mean (of duplicates) calculated from log₁₀ transformed copy number values. The left column is NLR data from model 4, the right column is CT-derived values. The errors observed seem to be independent of mean values. A 95 percentile of these data can then be calculated for evaluation of assay performance. Generally, the intra-assay variation is lower in CT-method derived values.