No. This is my calculation from HPTuners for AFR error:

100*([USER.9004]-[PID.6000])/[PID.6000]

USER.9004 is my wideband calculation through the A/C pressure switch. Replace USER.9004 with your wideband afr through the egr. PID.6000 is the commanded afr by the pcm. To calculate afr error for maf tuning you need to compare actual afr from the wideband to commanded afr from the pcm. Log this new afr error vs. maf hz and you will know what to change and how much.