I've gotten questions from people trying to choose between different bits of gear as to how to evaluate them--how does 2 more crit balance off against 2 less surge, things like that. Even though there are no combat logs, people have delved into the files and the available information to deduce most of the formulas in the game. (If you are interested, the closest equivalent to ElitistJerks seems to be SithWarrior.com.) The formulas that they use are pretty much the same composition as those in other games--with diminshing returns, multiplicative effects, and specific tweaks for specific abilities.
The short answer is that while leveling up, one point of any stat that matters to you is equal to any other stat that matters to you. The only trick is to make sure you know what stats matter to you.
Each character class has a primary stat. That stat always matters, and it adds some extra damage, healing (if you are a healer class), and crit chance.
Power on gear adds to the damage or healing bonus of everything you do. It always matters.
Force power only helps force abilities, and tech power only helps tech abilities. So if you are a force user (and you know who you are!) and you see a piece with tech power on it, count that as zero. It just doesn't matter to you.
Crit rating improves your chances of critting. It always matters. (Everyone has a minimum 5% chance to crit. Some classes get abilities that directly add crit chance.)
Surge increases the damage you do when you crit. It always matters. (Base crits do 50% extra damage, and if you had an infinite amount of surge you'd get up to 80% extra damage. Abilities that you have that increase crit damage add to that directly.)
Often, a secondary stat will add to some part of what you do. For example, strength always adds to melee attacks. If you are a jedi shadow, whose primary stat is willpower, the strength that you have will still add to your melee attacks with the lightsaber. But that's only part of the damage that you do, so while you'll see some of your bonus damage numbers go up with extra strength, it's not effective for everything, and I'd discount it. Similarly, Aim always helps with ranged weapon attacks, cunning always helps with tech attacks...but if those aren't your main stat, I'd ignore them.
Accuracy improves your odds of hitting. But, your basic attack (the default 1 key) starts with a 90% chance of hitting, everything else starts with a 100% chance of hitting. Yes, as the tooltip says, chances over 100% reduce the mob's chance of defending (dodging)...but evidence is that mobs have 8% defense. So any accuracy over 108% is wasted on dps, and any amount over 0 is wasted on healers. (Well...there is a claim that mobs get an extra 3% dodge for each level they are above you. So if you regularly fight stuff several levels above you, it's not totally useless...but really...)
Alacrity is a bit like WoW haste, in that it speeds up ability cast times and channeling times. It does not speed up DOT (Damage Over Time) abilities, however. And, it cannot reduce your cast time below the Global Cooldown of 1.5 seconds. So it is useful for few abilities, and for many classes can be ignored. If you find yourself using a lot of channeled abilities or 2 second casts it can be useful, otherwise, ignore it. I think they've kind of fumbled this stat, its not nearly useful enough to make interesting tradeoffs.
Defense is like dodge/parry, a successfully defended attack does nothing. Shield is like block, a successfully shielded attack will be reduced by the shield percentage. Both seem to work in 360 degrees, if the force is with you. And while many think the primary stat for a tank is Endurance, that doesn't add to the damage or healing bonus. ) If you are a DPS or healer, ignore defense and shield. If you're a tank, the gearing question is a bit more complicated due to the need to maintain agro, which is harder in TOR than in WoW.
There are a lot of other details to the formulas, but for doing gear comparisons you can pretty much ignore them. At 50, as the secondary stats start to climb, there are crossover points where you want more power instead of your primary stat, but for the typical gear you have while leveling up, it just doesn't matter. I went through my different level characters, and the difference in output from changing the primary stat vs. any of the useful secondary stats by the same amount was negligible.