Duration + DoT skills

I remember reading somewhere that modifying a duration of a DoT skill doesn't change its damage so effectively reducing its duration will increase overall dps. However from reading new chaos spells -https://www.pathofexile.com/forum/view-thread/1478438 it sounds like that's not the case. So which one is correct?

Nothing changed on new skills, they still state their base damage as 'X damage per second'. For duration to affect dps of DoT spells they need to be expressed as 'X damage over Y seconds'.

In first case (which is used in PoE), tampering with duration affects total damage inflicted by a single DoT effect but not its dps. In second case (common in Torchlight) duration affects dps and total damage stays the same.

I understand now thanks

Note that Skill Effect Duration will not even affect several sources of damage over time including poison, ignite, and bleed (except for Puncture).