CDspeed jitter versus DVDscan jitter

I've tested several DVDs on my Liteon 165H6. DVDscan always shows considerably more jitter than CDspeed. For instance if CDspeed shows the average jitter is 9.0%, DVDscan will show around 10.6%.

The difference between DVDscan and CDspeed varies between discs and ranges from 1.1% to 2.1%

Can anyone explain this?

Jitter may be analyzed in more than one way mathematically. It is clear to me that DVDScan estimates it as DD jitter, which is different from the DC jitter adopted by DVD specifications. I assume that the disc quality test of Nero CD-DVD Speed reports DC jitter for the DVD, but I am waiting for the answer from Erik Deppe.

Thanks for the info. I guess I can have some faith in the jitter scans. It seems CDspeed jitter is what we want. DVDscan jitter apparently is there only to confuse us.