scaling attributes and skills

[fig]

I have two tiers of attributes and one of skills that I'm trying to get to play nice together. I'll explain what I have so far, and then why it doesn't work. Hopefully, someone can help me out.

The core attributes (and derived attributes) are Physical (Strength, Agility, Fortitude), and Mental (Intellect, Perception, and Essence). The skills are just skills. Derived attributes range from -3 to +3. Combining the three attributes gets the Core attribute. So a Strength +3, Agility +1, and Fortitude 0 make a Physical +4. This makes the range-9/+9. Finally, skills range from 1-9 (or 10, I'm still deciding). Each of these three elements can be checked. A skill check is the skillx2, modified by the core attribute + 1d20 vs. TN or an opposed check. A core attribute check is just 10 +/- Core Attribute + 1d20 vs. TN or opposed check. Finally, a derived attribute check is...well, who really knows at this point.

There's already a problem between the Core attributes and skills. Checks need to be on the same scale, as sometimes a skill check will be opposed by an attribute check (derived or core). With what I have above, Skill checks can range from around -9 to 27 + 1d20, while Core attribute checks can range from 1-19, and derived attribute checks could be a few things, most of them different.

So, I want to set it up so these three checks can occur on the same scale. Furthermore, if I can do it without throwing fractions in the mix (like with the relationship between derived and core attributes), that would be golden. The only element that is immutable is that skills have to range between 1-9 (or 10), and skill checks have to be Skillx2 modified by core attribute. Can anyone offer advice? Thanks.

[Nathan W]

Hey fig, I'm not sure I can offer much help, but I just wanted to ask a few questions to possibly clarify some of the points you mentioned in your post. Hopefully then, myself or someone else, might be able to help more.

Just to make sure I understand: The "core" attributes (Physical and Mental) have their values derived from the "derived" attributes (Strength, Agility, Fortitude, Mental, Intellect, Perception, and Essence)? If that is the case, shouldn't the "core" attributes actually be the "derived" attributes. It's just a matter of language really, so it's no big deal whichever way you want to do it. I just want to make sure I understood that correctly.

Under what circumstances would attributes have a value lower than 1? What does a value of, say, 6 actually mean? How about -6?

Under what circumstances would core attributes be checked? Under what circumstances would derived attributes be checked?

The only element that is immutable is that skills have to range between 1-9 (or 10), and skill checks have to be Skillx2 modified by core attribute.

Why is that? I'm not questioning the value of the idea; I'm just wondering why this is important to your design? Knowing why that point is immutable might help us make suggestions without offering erroneous ideas or formulas.

My first observation, without having the benefit of the clarifications I asked for above, is that the math would be easier to match up if you weren't dealing with negative values.

[fig]

Actually, I got a pretty easy solution from rpg.net, so I'm all set. Thanks.