"Open Locks" chance of success

ineth

There's all kinds of conflicting information on the Internet about how the success of lockpicking is calculated in these games, so I've attempted to measure it myself.

I used the locked door to Apsel's workshop in the prologue of IWD:EE, which has a "Lock difficulty" of 25 according to NearInfinity.

My results:

| Open Locks | measured       | likely actual  |
| skill      | success chance | success chance |
+------------+----------------+----------------+
|         26 |        100.00% |           100% |
|         25 |         91.67% |            90% |
|         24 |         81.00% |            80% |
|         23 |         69.67% |            70% |
|         22 |         58.67% |            60% |
|         21 |         49.33% |            50% |
|         20 |         39.67% |            40% |
|         19 |         29.00% |            30% |
|         18 |         22.00% |            20% |
|         17 |         10.33% |            10% |
|         16 |          0.00% |             0% |

So it looks like you need an Open Locks skill score of at least Lock difficulty + 1 for guaranteed success, while Lock difficulty - 8 or higher at least gives you a chance at success.

Still open questions:

• Does this rule hold up for all Lock difficulty scores?
• How does Luck/Fatigue affect the probabilities?
• Are there any other factors that don't change the visible "Open Locks" score listed on the character record screen, but still affect the probabilities?

---

My raw measurements data:

Open Locks = 26
number of measurements = 300
measurements = 300y
success chance = 100.00%

Open Locks skill = 25
number of measurements = 300
measurements = 4y n 20y n 23y 2n 12y n 11y n y n 2y n 22y n 34y n 28y n 16y n 4y n 9y n y n 31y n 2y n 2y n y n 21y n 8y n 5y n 3y n 8y n 5y n 2y
success chance = 91.67%

Open Locks skill = 24
number of measurements = 300
measurements = 7y n 3y n 6y n y 2n 7y 2n 4y 2n 11y n y n 4y n 4y n y n 9y n 4y 2n 14y 2n y n 5y 3n y 2n y 7y 2n 13y n 2y n 2y n 7y 3n 3y n 9y n 3y n y n 7y 2n 10y 2n 8y 2n 2y n 2y 2n y n 9y n 2y n 8y n y n 8y n 3y n y n 14y 2n 12y n 24y
success chance = 81.00%

Open Locks skill = 23
number of measurements = 300
measurements = 5y 2n y 3y n y n y n y n y 5y n 2y 2n 5y 2n 2y n 6y n y n 3y n 2y n 4y n 8y 3n y 2n y 5y n 4y n 2y n y n 2y n y n y 2n y n 2y 2n 2y n 4y n y 2n 4y n 8y 4n 3y n 2y n 9y n 4y n 4y n 3y n y n y n y 2n 4y n 3y n 2y 3n 4y n y 3n 2y n 2y n 4y n y n y n 4y n 2y 3n 2y 2n 7y n 3y n 2y n y n 2y n 2y 3n 7y n 3y n y n 4y n 6y n 2y n y n 3y n 3y n 9y n y n y
success chance = 69.67%

Open Locks skill = 22
number of measurements = 300
measurements = 2y n 2y n 5y 5n 6y 2n y n y n 3y n y 2n 5y 3n y 4n 3y n y n 6y 2n 3y n 5y n y n 3y 2n y 3n y n y 3n y n y n 6y n y 2n y n 3y 2n y 2n y 4n 2y n 3y n y n 2y 2n 2y 2n y n 2y 2n 2y 2n y n y 8n 6y 4n 2y n 3y n 4y 2n 3y n 3y n 4y n 2y n y n y 2n 6y 2n 2y n 3y 2n 2y n y 2n 2y n 5y 2n 4y n 4y n 4y n y 2n 4y 2n 2y n y n 3y n y 2n y n 2y n y n y 2n y 5n y n y n y n 8y n y
success chance = 58.67%

Open Locks skill = 21
number of measurements = 300
measurements = n y 2n 6y n y 2n 2y 3n y 3n y 3n 5y n y 3n y n y n 3y 3n y n y 3n 2y 5n y n y n y n 4y n 2y n y n y n 2y n y 7n 2y n 2y 3n y 2n 2y n 5y n y 2n y n y 2n y n 2y 4n y 2n y 2n 2y n 4y n y n 2y 3n 2y n 2y 2n 3y n 2y n 2y 2n 3y 4n 3y n y n 3y n 3y 2n y 2n y n 3y n 2y n y 7n y n y n 2y 5n 2y 2n 3y n 2y n y 2n 5y 5n y n y n y n 6y 2n y n y 6n 3y n y n 2y n 2y n 2y n 3y n 2y 5n y 2n y 2n y 3n
success chance = 49.33%

Open Locks skill = 20
number of measurements = 300
measurements = n y 3n y 3n 3y n 2y n y 2n y n y 7n y n 2y 3n y 2n 2y 2n y 2n y 2n y 2n y 5n y 3n 7y 3n y 2n 3y 3n y n 2y n 2y n 2y n y n 2y 2n y 7n y 7n y 3n 3y 2n 2y n 3y n 3y 6n 3y n 3y 9n y n 3y 5n y 3n y 2n 2y n y 2n y 4n y n 2y 2n y 4n y 5n 3y n y 4n y 2n 2y n 2y 2n 3y 2n y 2n y 2n y n 2y n y 2n y n y 2n 2y 2n y 8n y 2n y 2n y 4n 4y 2n 2y n 2y n y n y n y 2n y 2n y n 2y n y 5n
success chance = 39.67%

Open Locks skill = 19
number of measurements = 300
measurements = 4n y 3n y 7n y 6n y 2n y 8n y 2n y n y 2n 2y 3n y 4n y n 2y 2n y 3n 2y 5n y 6n y 2n y 6n y n y 6n 2y 2n y 5n y 2n y 6n y n y n 2y 2n y 4n 2y 4n y 2n y 2n y n y n 2y 4n 2y n y 4n y 5n 2y 2n 3y 3n 2y 3n y 2n 2y n 2y 7n y 4n y 4n y n y n y n y 2n y 3n y 3n y 2n y 3n y n y 6n y n y 2n y 5n y 4n y n y 5n y n y 5n y n y 3n y 3n y n y 2n y 4n y n y 3n 2y n y
success chance = 29.00%

Open Locks skill = 18
number of measurements = 300
measurements = y 2n y 2n y 4n y 2n y 14n y 3n y 2n 5y 3n y 4n y 5n 2y 6n 3y 5n y 3n y 3n y 3n y 2n y 4n y n y 2n y 7n y 7n 2y 2n 2y 4n y 2n y 13n y 6n y 2n y 7n y 9n y 12n y n y 2n y 8n 3y n 2y 8n 2y 6n y n y 6n 2y 2n y 2n 2y 2n y 2n y 3n y 6n y 4n y 2n y 7n y 13n y 14n y 3n y
success chance = 22.00%

Open Locks skill = 17
number of measurements = 300
measurements = 18n y 4n y n 2y 9n y 7n y 3n y 8n y 8n y 4n y 14n y 3n y 13n 2y 11n y 6n y 14n y 6n 2y 7n y n y 5n y 3n y 12n y 17n y n 2y 25n y 11n y 6n y 14n y 38n
success chance = 10.33%

Open Locks skill = 16
number of measurements = 300
measurements = 300n
success chance = 0.00%

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Key:
    y = success
    n = failure
    <number>y = consecutive run of <number> successes
    <number>n = consecutive run of <number> failures

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Common context for all data series:

Game = IWD:EE v2.5.17.0
Character = Elf Bounty Hunter, 15 DEX, Level 1. (Shouldn't matter, since racial and DEX modifiers to the Open Locks skill are rolled into the skill score shown on the character record screen, and that's the score I recorded for each data series.)

kjeron

Open Locks, Bash Doors, and Disarm Trap all have a 1d10 modifier, affected by luck.
For Success you need: Skill - 1 + 1d10 > Difficulty
@Bubb reported the modifier back here.

Detect Trap is just a straight: Skill >= Difficulty.

Edit: link fixed - not sure what happened.

ineth

kjeron wrote: »

Detect Trap is just a straight: Skill >= Difficulty.

Interesting. Do you know when that check decides to kick in (just at a random time once per round?) and how the distance between Thief and trap affects things?
EDIT: answered by Bubb here.