Abundance versus codon adaptation index (CAI). Each point on the plot corresponds to a protein characterized by two values: abundance and CAI. The Spearman rank correlation coefficient rs between log-copy number and CAI is 0.5 and the Pearson correlation coefficient is 0.57 indicating a good non-random (p-values both < 10-16) correlation with some variance. The dotted line is a linear regression between log(copy number) and CAI, the solid line a loess local fitting curve.
Ishihama et al. BMC Genomics 2008 9:102 doi:10.1186/1471-2164-9-102