Inspired by the closed question: DnD Next Hitpoint Inflation,
There have been claims of HP inflation in dnd-next, and there certainly were increased in the absolute value of HP in 4e. In order to objectively assess these claims, we must look at the mechanical-theoretical model of damage across all editions of D&D.
Therefore, at level 1, all things being equal, how many rounds does it take a goblin to drop a Fighter, a thief, and a Magic-User?
In order to ask this question: we must assume conservative builds on all sides, the average hitpoints of each of these classes, and the average damage (including to-hit adjustment) of the goblin in every edition.
If there is significant deviation in 4e, this might provide me with the necessary data to house-rule 4e into a "gritter" experience for purposes of a Break & Enter game.
Best Answer
Compiled Results from Other Answers
DnD Next numbers include calculations from both the 1st and 2nd playtests.
Summary
AD&D: improved fighter & rogue survivability
3.5: slightly improved wizard survivability, and pulled fighter survivability down considerably (trend towards narrower range begins)
4e: improved everyone's survivability, though mostly rogue & wizard, further narrowing the spread
4e's MM3: reduced all survivability and tightened the spread again
DnD Next (playtest 1): slight reduction in fighter survivability to tighten the spread even more
DnD Next (playtest 2): major reversal of the reduced spread trend
Thoughts
From 3.5 on, every edition change (including the switch inside 4e from MM1 damage expressions to MM3 damage expressions) has essentially worked to reduce the survivability gap between the toughest and weakest PCs, primarily by bringing the fighter down but in 4e's case by bringing the wizard up. We're down to fighters lasting about twice as long as wizards, rather than the 5-7 times longer from OD&D and AD&D. Rogues have moved from being only marginally more durable than wizards to being about halfway between wizards and fighters. Base wizard survivability has approximately tripled since OD&D/AD&D, and later editions have given them more options for improving it further.
A Note on HP Inflation
As of playtest 1, worries about hit point inflation in D&D Next over 4e appear unfounded: D&D Next PCs last about as long as 4e PCs do when using the new 4e monster damage values, and only slightly less than 4e PCs do when using the original 4e monster damage values.
As of playtest 2, DnD Next hit points are back to pre-3rd standards.