DR and the parry/dodge ratio

[Stricker]

It's as if my mind is blank, I cannot remember what diminishing returns mean to us as tanks, and what it has to do with the parry/dodge ratio, whatever that is. I remember reading about it before, but I've completed forgotten what the deal is. Can anyone direct me to any relevant topics on this matter?

Regards,
Hopelessly confused dwarf

[lythac]

The ratio is -

(character_sheet_dodge-10%)/(character_sheet_parry-10%) = 1.88

Diminishing returns on avoidance do not work like diminishing returns on stuns! There's a common belief that if you avoid an attack, your chance to avoid subsequent attacks is reduced. This is not true - read on!

What are diminishing returns? One definition puts it this way: The principle that further inputs into a system produce ever lower increases in outputs. Basically, you get less avoidance for every point of rating than you got for the last one.

And a nice visual -

As a first approximation, let's assume that we're starting with 689 defense from gear, and re-run the calculation for each additional point of rating:

Both of the linked posts have all the information you will ever want to know about DR. The Tankspot thread has a guide feel to it, which is unsurprising as its in the guide section.