Sneak (Fallout: New Vegas)

Sneak is a skill in Fallout: New Vegas. It determines the chance of being detected while sneaking.

Initial level

 * $$\text{Initial level}=2+(2\times\text{Agility})+\left\lceil\frac{\text{Luck}}{2}\right\rceil$$

Example: A starting Agility of 5 and Luck of 5.
 * $$2+(2\times5)+\left\lceil\frac{5}{2}\right\rceil=15$$

Most aspects of the Sneak skill are the same as for Fallout 3. This includes the initial statistic, the sneak meter, stealing and pickpocketing, and Sneak Attack Criticals. Exceptions and new aspects are described below.

Sneak in quests and exploration

 * 25 Sneak can be used to convince Trudy to fight the Powder Gangers as an alternative to 25 Speech.
 * 50 Sneak is required to smuggle improved holdout weapons into New Vegas Casinos, as well as the interrogation room at Camp McCarran.
 * 50 Sneak is required to convince Mister Holdout to sell improved holdout weapons.
 * 75 Sneak is needed to convince Father Elijah that hiding in the Sierra Madre is easy, and effectively get him to come down into the Sierra Madre vault.

Ways to improve Sneak

 * Permanent
 * Leveling up (up to 10 + INT/2 + 2 with Educated perk)
 * Chinese Army: Special Ops Training Manual (+3 or +4 with Comprehension perk)
 * Agility Implant (+1 depending on current Agility, a perfect Agility of 10 will see no benefit)
 * Tag! (+15)
 * Skilled (+5)
 * Temporary
 * Fire ant nectar (+2-8 depending on current Agility, a perfect Agility of 10 will see no benefit.)
 * Recon armor (+5)
 * Stealth Boy (+100, +75 cloaking field)
 * Chinese stealth armor (+5)
 * ¡La Fantoma! (+10 or +20 with Comprehension perk)
 * Assassin suit (+10)
 * Salt-Upon-Wounds' helmet (+5)
 * Stealth suit Mk II (+15 or +25 with the Firmware 1.1 Upgrade)
 * Dead Horses stalker armor (+5)
 * Blood-Nap (+10)

Bugs
The "Sneak" skill has no difference in effect from 50 to 100. Only factors are the amount of light, running (pre-perk), stepping on some obstacles, and line of sight.