Steal Technology

[Aabraxan]

And you'll need cash.

 

[Jazzmail]

Which is generally more efficient, producing gold(50 turn tech) and stealing technology or max research?

Since nobody came up with any figures, I thought I'd do some research myself.
The cost for setting up a careful theft is given in a formula:

cost = distance * level + base * tech * techrate / 100, where

base = 10 for players in all non-modded games apparently...
techrate = 160, 200, 240, 320 or 400 (mapsize)
tech = the variable for each technology
distance = #tiles between their city and yours
level = 1,2 or 3, for towns, cities, metros resp.

The factor (distance * level) is negligable for advanced techs. We now have:
cost = tech * techrate / 10

The operation may fail so it may take a few tries. The odds are 0.75*0.80 = 0.60 for a regular spy. Let's factor this into the equation:
C = tech * techrate / 10 / 0.6 =
C = tech * techrate / 6

I found a formula for research on the forum:
B = [ techrate * [10*tech * (1 - N/ [CL*1.75]) ]/(AICF * 10) ], where

[] = round down
AICF = AI cost factor. Let's assume the least favourable value of 6 (for diety level)
N = number of civs on the diplomacy screen that have discovered the tech.
CL = number of civs left in the game

The player's civ doesn't have the tech while AI will easily trade among AI on diety: (1 - N/[CL*1.75]) = 1 - 6/12 = 0.5
Now we know how many beakers:
B = techrate * [10 * tech * 0.5] / (6 * 10) =
B = techrate * tech / 12


Now we can finally compare research to espionage (diety level, any mapsize):

C / B = tech * techrate / 6 / (tech * techrate / 12) = 2.
Espionage actually cost double compared to doing our own research. Unexpected. Probably because I factored in the chance of spy failure.

 

[macthk]

I suppose my options are a bit different in Vanilla, cause I don't have the option to plant spies. I just get the same two options steal and investigate.

 

[Aceman101]

You can plant spies in vanilla but it is more difficult. Do you know the Intelligence Agency? You get that when you research Espionage, After you research espionage, build the Intelligence Agency in one of your city's and when it is built click on the little icon that appears next to the box that shows how much turns left until something is built. It should be a sort of grey icon. So when you click on it, a box will come up. Then click "Initiate Espionage" or something and there will be an option to plant a spy.