How does weapon mod Add x amount elemental damage work with regard to dps?

Hey guys, still very new to PoE and trying to understand how this mod affects dps. During the 2 week flashback event, I decided to give this mod a go on a wand/scepter, I believe the mod I rolled was adds 4-60 lightning damage to spells. In my mind I was like woohoo, 60 damage. Yet when I compared the mod to a similar statted wand with a 20% increased spell damage mod, the added lightning damage mod actually gave me a significant dps boost in comparison.

How is the 32 average dps lightning mod giving me more bang for the buck than a flat 20% increase? My toon at the time was doing around 10k with spark....an additive 20% seems a hell of a lot more than 32 added average.

Confused an obviously stupid :/

Two reasons, one is that flat added damage is base damage, it adds to what you see on the skill gem, not on the tooltip. And the other reason is increased damage is additive and you probably already have a ton of increased damage on your char, going from 380 to 400% increased damage isn't much of a difference.

Flat added damage is applied before modifiers, that's how. Also, "increased" modifiers add together to form a single multiplier, so the higher you stack them, the less impact they have comparatively.

Example:
- Spark hits for a base 100 damage, and you have +300% increase. The final hit is 100 * 4.00 = 400.
- You get another 20% increase. Damage is now 100 * 4.20 = 420.
- Instead of the 20% increase, you add 50 damage, so the base becomes 150. With the +300% increase, you now hit for 150 * 4.00 = 600.

These aren't necessarily realistic numbers, but you see the point. Flat added damage can be a very powerful way of boosting the damage of skills with a low base damage.

Thank you raics and suszterpatt, that makes a lot of sense. Obviously I do not grasp mechanics well because I did not know how the flat damage was added to base damage of the skill. Now things make much more sense, thanks again!