Talk:Trading and item pricing
Math in the Trader Attitude section seems wrong.
A trader's Attitude score represents how friendly a trader NPC is with a certain character. Each point of Attitude modifiers prices by 0.25%. The maximum attitude modifier at 100 Attitude is 2.5, or a 25% price adjustment compared to 0 Attitude.
Attitude modifier = Attitude * 0.0025
I think that 2.5 in the bold section should be 0.25, which is 25%. The equation is accurate and 100 * 0.0025 = 0.25, not 2.5.
bit of a mess
Cleaned up this page because it was inconsistent and contained errors. For example, it said "Favorable modifiers are negative and unfavorable ones positive" while the difficulty modifier for tactician is -0.5 and for explorer it's 0.5, a seeming contradiction with the previous statement. That's of course because this modifier is SUBTRACTED from the total modifier, but this will nonetheless confuse people who aren't very mathematically minded. And if you're going to make statements about positive and negative modifiers you really shouldn't subtracting in formulas as that will only complicate interpretations. Better to not make vague statements about positive and negative and let the formula speak for itself.
The total modifier is reduced by 0.1 per persuasion point, not 0.01. No doubt an error which snuck in because of the "1%" which was mentioned in that paragraph.
Which brings us to the percentages. Using percentages is popular, but as a rule of thumb it's better not to use them unless there's zero ambiguity what you're talking about. Many people seem to forget that a percentage represents "a part relative to a whole", and if it's not unambiguously clear what whole you're talking about the percentage loses its meaning and becomes confusing. For example, the page claimed "Each Persuasion modifier point changes prices by 1%". 1% of what? 1% of the base value? 1% of the current value? That's not the same! It's not even correct in either case! If it's 1% relative to the current value then other modifiers (such as difficulty) will also play a role and thus the relative value of a single persuasion point isn't a constant. And if it's 1% relative to the base value it's mathematically incorrect because increasing a point in persuasion comes down to adding an additional term of "-0.1 * base value", i.e. it's TEN percent of the base value. As a further example of how percentages are confusing and to avoided if it's not explicitly stated relative to what, the page seemingly contradicts itself. It said "the difficulty modifier is 0.5, meaning all characters receive a 20% favorable bonus to prices" but it also said "The maximum attitude modifier at 100 Attitude is 0.5, or a 50% price adjustment compared to 0 Attitude". So it claimed that 0.5 is both a 20% and a 50%, and that's because both percentage are talking about completely different things. The 20% refers to 0.5 (difficulty modifier) relative to 2.5 (base modifier) (which, btw, is ONLY relevant if all other modifiers are zero!). And the 50% is relative to the base value of the item.
In conclusion, it's always better to use absolute values and avoid percentages unless it's unambiguously clear what they are relative to. This is especially true when dealing with an audience where not everyone is mathematically versed enough to spot that the meaning of percentages change from paragraph to paragraph because the context is different
— unsigned comment by 81.82.46.46 (talk) 16:12, 11 November 2023
- Great comment. I especially agree with the "percentage-problem". (Unrelated to this page, it also occurs e.g. for successful attack rolls, where people say e.g. "Bless increases the attack chance by 5-20%" etc.)
- But there's still a problem: There's a section called "Persuasion skill modifier". Afaics what they mean is the Persuasion skill VALUE. To my knowledge there's no such thing as a "Persuasion skill modifier", so even worse, this section title implies that, here, this new modifier is defined/explained. But the section ACTUALLY defines/explaines a "Persuasion Modifier" (which is a 1/10 of the Persuasion skill value, right?). So I suggest the section title be changed to "Persuasion modifier" and the term "Persuasion skill modifier" to "Persuasion skill value" (or simply "Persuasion value"). Gewinnste (talk) 14:40, 4 March 2024 (CET)
Charisma Modifier
Something that seems to go unmentioned is that a character's charisma modifier automatically applies a discount when buying items (and a markup when selling them). Or at least, that's what I'm seeing in tactician mode. --68.100.93.66 21:06, 17 November 2023 (CET)
- the page mentions the effect of your persuasion skill on prices, your CHA influences your persuasion skill.
Discount Percentage
I was puzzled by what is shown in the discount percentage, so I did a bit of investigation resulting in the following findings:
price_modifier = (3.0 - attitude / 200 - persuasion / 10) merchant sell price = base price * price_modifier
notes:
| persuasion | attitude | discount % | price_modifier |
|---|---|---|---|
| -1 | 0 | +3% | 3.1 |
| 9 | 100 | -88% | 1.6 |
| 9 | 0 | -43% | 2.1 |
| 4 | 0 | -15% | 2.6 |
| 0 | 0 | 0 | 3.0 |
discount_percent = (1 - 3.0 / price_modifier) * 100 Tulth (talk) 23:09, 3 April 2024 (CEST)