This page gives an overview of the relation between statistics, given in numbers and formulas. Note however that these numbers and formulas might change because of patches being applied (balancing).
Whenever a resulting number has a fraction, then the result is rounded down. So 23.5 will result in a value of 23.

Primary stats in Numbers
Several secondary stats are derived from primary stats. The way that they are derived is not always the same for every way. The following shows in detail what the relation is between the primary stats and the calculated secondary stat.

To this calculated damage, the weapon damage is added.

Weight
The maximum weight you can carry is caluclated as follows:

Maximum Weight = Strength * 20 + 1600

You are encumbered when the current weight being carried is 3/4th of the maximum weight. You can't move anymore when you exceed the maximum weight.

Chance to hit
Each monster has a base chance of being hit. The higher the number the more chance it has to being hit. But also it's defense and your characters offense value is important.

The calculation is performed as follows:

ChanceToHit = Monster_ChanceToHit + Character_Offense - Monster_Defense - Monster_Level.

Added to the above calculated chance is the weapon chance to hit value.

So the higher the level and defense values of the monster the harder it is to hit it. Your only direct influence to this 'Chance to hit' is your offense value. Which is improved by increasing your agility.

Note that the Chance to hit value will be limited between 5 and 95%.

Protection
You can wear armor on different parts of your body. Your maximum total protection will be 100% and is distributed as follows:

Whenever you are hit, the hit is being placed on one of the parts on your body. To determine where it is hit, a random number between 1 and 100 is generated. The hit is being placed where the 'cumulative hit' is equal to that number.
When you are wearing protection for that body part then the armor value of that protection is deducted from the damage. When you don't have any protective armor placed there then the full damage is inflicted.

Resistances
There are four resistances; lightning, fire, poison and spirit. The higher the resistance you have the less damage will be inflicted to you. The following formula is used for that:

Damage reduction = (resistance * damage) / 100

The reduction will only be made for the damage the resistance applies to.