Effect of utilising different sources of information on the estimation of λ. Variance estimates from the external datasets (Table 1) and gene length are used to aid in the estimation of the common variance functions of one hundred comparisons of n B6 and n D2 mouse striatum samples. The average λ value is plotted for each n comparison and information source for n ranging from two to five. λ is the ratio of the expected and average squared error of the gene sample variance to the common variance. The information source "None" corresponds to using no extra information, "Striatum" the RNA-Seq samples from Polymenidou et al (2011) and "Striatum Microaray" the microarray striatum samples from Bottomly et al (2011). The information sources have been sorted by their λ values for n equals two.