I have constructed a simple spreadsheet that computes the average damage reduction coming from gear for a Protection Warrior. I am making it accessible to the community, as googling the phrase 'Protection Warrior Spreadsheet' returns a page of people asking for one.
It is up to date to 4.2 to the best of my ability. It currently gives relative stat weights for our defensive stats besides stamina and reforging advice for minimizing average damage taken.
All serious work (discovering formulas, constants, testing in game and so on) was done by others and found by googling. The only testing was to match the spreadsheet against my gear and character-sheet. All errors belong solely to the author.
To use the spreadsheet, please make a google documents account and copy it.
Yellow cells require input from the user. Green cells mark the comparisons. The Red cell marks what fraction of the combat table is covered by dodges, blocks, and parries. This number needs to be above 75 for the computations involving shield block to be accurate, which I assume for all stat comparisons in pages 2 and 3. Blue cells show you what fraction of dmg is removed purely by your gear.
Hopefully the spreadsheet will be of some use to the community.
Edit: Wow, there's another spreadsheet 3 posts down. That would have saved some time.