Distributions of stool DNA markers (BMP3, NDRG4 and β-actin) by study, (A) standardized to the mean and standard deviation within the study of origin and (B) after center and scaling the data.
* Copy numbers of BMP3 and NDRG4 were standardized by beta-actin
** Left and right Y-axes show ratios for the standardized markers and copy numbers for beta-actin PCR products, respectively