I like keeping as many people alive as possible through persuasion :3
I have Charisma 6 and Luck 2 and I've passed maybe 1/5. Pretty sure it's my Luck that's dragging me down.
My character has 8 Charisma and still fails speech checks. Most likely even if you have 10, you're not going to pass speech checks 100% of the time. Of course you're also talking to a guy who has literally failed speech checks in New Vegas where I had a 95% chance of success... so maybe it's just me.
Mine has 9 charisma,8 intelligence and 7 luck, failed some speech checks as I perceive no difference from the plot everyone is progressing.
I'd also like to point out it's percentage based, not a hard check. If you have a save close to a speech check, you can re-load to try again.
its random its just more likely with high charisma and luck, you can pass all of them with low if you are lucky in real life even without charisma or luck in game
Yep, same as in Fallout 3, they just don't display the percentage chance for success now. Looks like Bethesda learned (and implemented) pretty much nothing from New Vegas.