I'm having trouble reconciling the formulas shown on the USEP Wiki with actual in-game results.
I tested with alchemy, speech, and smithing since they are easily tested.
Test Conditions:

• Loaded Skyrim 1.5 with no mods - strictly vanilla (In fact, I uninstalled every mod so Skyrim was default)
  
• Deleted Skyrim.ini and SkyrimPrefs.ini and let the game generate new files.
  
• Started a new game and created the default "prisoner" by coc qasmoke at the menu screen.
  
• coc to whiterunarcadiascauldron
  
• Added 100 blue mountain flowers and 100 butterfly wings to player inventory.
  
• Added 11 iron ingots and 11 leather strips.
  
• Added 10000 gold.
  
• No buffs or enchanments, just the "out of the box" level 1 Nord.

Prior to my test, I loaded many games, always with the vanilla Skyrim default prisoner and manually increased alchemy, speechcraft, and smithing (player.advskill alchemy XXX) until I was able to determine the XP needed for the next level to 4 decimal places.

Then I loaded yet another game, only this time I loaded the save I created with the default player with all the added inventory.

According to the USEP:

Skill Impove Mult * Skill level[sup]1.95[/sup] + Skill Improve Offset

is the xp needed to advance to the next level.

Skill Use Mult * Base XP + Skill Use Offset

is the skill use xp


Actual numbers:
Alchemy, Level 15 to 16. It took 34 creations of restore health to advance.
XP needed formula: (.16 * 15^1.95 + 65) = 379.4111
XP required, manually: 505.8816
XP gained formula: (.75 * (34*14) + 0) = 357 (Base XP = gold value of potions)

Smithing, Level 20 to 21. It took 11 created iron daggers to advance.
XP needed: (.25 * 20^1.95 + 300) = 386.0892
XP required, manually: 386.0892
XP gained: (1 * (25 + (3 * 10^1.95 ))) = 292.3753 (Base XP = 25 * (3 * item value^1.95 )

Speech, Level 20 to 21. It took 5719 gold buying / selling transactions to advance.
XP needed: (2 * 20^1.95 + 0) = 688.7133
XP required, manually: 1913.0927
XP gained: .36 * 5719 = 247.9368 (Base XP = gold used in transactions)


Anyone have any ideas about why the discrepencies? As you can see, only some of the formula values are correct.
Either there are other in-game factor(s) I'm not taking into consideraton or the formulas are wrong or possibly calculated differently for each skill.

isn't anyone curious about this?