A number of monsters are described within the rules as being stealthy with it typically noted as being X times that of an average human. So what is the stealth of an average human?
According to [83.1], "Also, when compared to non-adventuring members of their respective races, adventurers have, on the average, 50% higher numerical totals in all characteristics." From 5. Characteristic Generation, we know that the range of values for a characteristic is normally between 5 and 25 which gives us an average of 15. From that we can determine that the average human characteristic, such as Agility, is 10. [Whether or not average humans having characteristics of 10 makes any sense is a topic for a different post.]
Using the formula provided by [83.3] for determining stealth, ([3 x Agility] + [5 x Rank] ), and assuming average humans have no Rank in stealth, this would give the average human a stealth of 30%. However this contradicts information found in the Monsters section of book 3 under the entries for [66.1] Apes and Prehumans and [66.2] Felines.
[66.1] Apes and PrehumansThere are two ways to read those statements. The first is that the value given in parenthesis is the stealth for an average human. As the value given under Apes and Prehumans is 30 that appears correct until you see the value of 40 given under Felines. So the second way to read these lines is that the numbers in parenthesis are the stealth value for the monsters. This jives with the three times and four times of the descriptions. Sadly these values suggest that an average human has a stealth of 10 which is only one times Agility and not the [3 x Agility] base value from [83.3]. Further these naturally stealthy creatures would have pretty poor values for stealth as the values are then reduced by the greatest Perception value of those who might be able to detect them per [83.3].
"They have three times the stealth of an average human (30) and ..."
"All felines will possess four times the stealth of the average human (40)."
Maybe the value of 40 given is a typo (in all three editions). So calculating the stealth for a Baboon per [83.3] we get (3 x 20) or 60. That's not three times 30 nor is it three times 10. It's certainly better than 30 but is still not very impressive.
There are a few more entries in the list of Monsters that also note their stealth.
[70.2] Fairy FolkNo real help there as stealth is once again expressed as a multiple of average human stealth.
"They have 3 to 4 times the stealth of an average human and will, as a result, seldom be seen unless they wish to speak with a party."
"They will have twice the stealth of humans.
"They are also 3 times as stealthy as humans, ..."
So does it really make sense to express the stealth of a monster as some number times that of the average human? If I say that one fighter is three times as good as another in the context of DQ I think most of us would assume three times the Rank and not the total Strike Chance of which Rank is only a part of the calculation. With that assumption a Rank 6 fighter would be three times as good as a Rank 2 fighter. But maybe that isn't a good set of skills to compare. How about Horsemanship? The formula for Horsemanship is [(WP + mAG)/2 + (8 x Rank)] per [83.2]. The Rank multiplier of 8 means Rank plays a significant factor in how good one is in Horsemanship. Stealth's Rank multiplier of only 5 means Rank plays a lesser part but is still significant at higher Ranks.
If not expressed as a multiple of average human stealth then what? One idea is to assign those Monsters noted for being stealthy a Rank in Stealth, probably in the 1 to 4 range, and use that 2 to 4 times value to determine a Stealth Bonus (20% to 40%) much like that given for Elves and Halflings. Then change the formula to be like this:
Stealth = ([3 x Agility] + [Stealth Bonus] + [5 x Rank] )The bonus would need to be in the 20% to 40% range to have any noticeable affect. Looking at the average Baboon again the stealth would become ([3 x 20] + 30% + [5% x Rank]) giving a range of 90% to 110% which is pretty stealthy and actually starts at 3 times the average human. Those monsters with high agility such as Felines would be nearly undetectable but this is to be expected.
In my own campaigns in the past I've always calculated the stealth for individual Monsters per [83.3] and then given them Ranks and/or bonuses depending on the type of creature.
What have you done?