Base dodge varies on class, base agility on race.
Here's a deathknight (not our guild's since he is not in tank gear now, just a random DK)
(
The World of Warcraft Armory)
Has stoneskin gargoyle
117 defense skill
483 dodge rating
527 parry rating
134 agility from gear
110 agility when naked
3.463600 base dodge for a deathknight
73.529412 agility/1% dodge for a deathknight
k = 0.956
39.34799 dodge rating/1% dodge undiminished
49.18499 parry rating/1% parry undiminished
Has 5/5 anticipation
Dodge
Undiminished dodge = anticipation + base + dodge from naked agility + stoneskin gargoyle
= 5.00 + 3.4636 + (110/73.529412) + 1
= 10.959600%
Pre-diminished dodge = dodge from defense + dodge from rating + doge from agility on gear
= 117 * 0.04 + 483/39.347990 + 134/73.529412
= 18.777487%
Diminished dodge = 1/(1/c + k/pre-diminished)
= 1/(1/88.129021 + 0.956/18.777487)
= 16.061927%
Total dodge = 10.959600 + 16.061927
= 27.021527% (armoury shows 27.02%)
Parry
Undiminished parry = base + stoneskin gargoyle
= 5.000000 + 1.000000
= 6.000000%
Pre-diminished parry = parry from defense + parry from rating
= 117 * 0.04 + 527/49.184990
= 15.394651
Diminished parry = 1/(1/c + k/pre-diminished)
= 1/(1/47.003525 + 0.956/15.394651)
= 11.994076%
Total parry = 6.000000 + 11.994076
= 17.994076% (armoury shows 17.99%)
Miss
Undiminished miss = base + stoneskin gargoyle
= 5.000000 + 1.000000
= 6.000000%
Pre-diminished miss = miss from defense
= 117 * 0.04
= 4.680000%
Diminished miss = 1/(1/c + k/pre-diminished)
= 1/(1/16.000000 + 0.956/4.680000)
= 3.748498
Total miss = 6.000000 + 3.748498
= 9.748498%