Improved accuracy using updated probe set definitions. The accuracy between measured log2 ratios using RT-PCR and microarrays were compared for microarray measurements using the original (NetAffx) and updated probe set definitions. The accuracy was obtained by calculating the slope from a linear regression comparing the obtained log2 ratios from the microarray to those estimates obtained using RT-PCR, where the microarray estimates were obtained using the different probe set definitions. A slope of 1 would indicate perfect accuracy. The mean accuracy across five different labs is plotted together with the standard deviations.