Figure 4

Pairwise variation to determine the optimal number of normalisation genes. The optimal number of genes was determined separately for pulmonary artery (A) and lung (B) in combined BSD and control samples. A large pairwise variation V indicates that the added gene has a significant effect and should be included in the normalisation factor calculation. Based on the pairwise variation for pulmonary artery and lung addition of a third reference gene does not improve normalisation in either tissue.