Maybe this is obvious or stupid, but I suck at the maths. It might even be in a book and I skimmed past it.

At what point is it more effective to default to a skill's linked attribute rather than take the skill at a low level? Is there a rule of thumb, like "don't bother taking skill x(QCK) at 2 if you have quickness 6 or above."

It really depends on the skill -- can you eat or otherwise reduce the penalties for defaulting?

Arguably, any time you have a stat that massively outclasses the skill or even the potential of the skill, defaulting is the order of the day.

Athletics leaps to mind -- Trolls, samurai and similarly large creatures are better off using their Body, even with the default penalties.

-Siege

True, but I always consider the lack of ability to use pools when defaulting a big loss. You take a +4 (or +3 or +2) and you can't use pools or you roll a lower number of base dice but augment with pool dice and don't have a TN modification.

When you're acting without the ability for pools, however, it can be basically the same.

It's impossible to work out the math without making some assumptions about typical TN penalties. Based on my experience, I think 2 is about even, and 3 skill puts you ahead in most situations.

I was really annoyed last night when my character was forced to pick up an Assault Rifle instead of his standard SMG. The weapon he grabbed had no Smartlink, and only 1 recoil comp. The rules say you can't default to a skill or attribute if the TN before defaulting penalties is 8 or higher. I could not AIM (limit on AIM is 1/2 the appropriate skill for that weapon, and I did not have the appropriate skill). I could shoot only one burst each Action, because recoil on a second burst made the TN too high. And once the Target started running I couldn't shoot burst fire at all due to the "Target Running" penalty, I had to switch to Semi-auto.

Last night I greatly wished I had Assault Rifles at 3. (I also wished I had more on than a hospital gown. Way too much "Richard Hatch" was exposed.) Even Assault Rifles at 2 would have been more useful than my defaulting to SMG (7) plus 3 pool.

Hence my notation regarding penalties -- combat skills live and die on a +1 or a +2.

By comparison, look at skills that don't offer pools and penalties being relative and usually non-critical.

Athletics
Any social skill (Elf with Charisma 8?)
Stealth

If the attribute is, as OT mentioned, in the 3 or 4 range, a skill can be purchased with minimum fuss and karma. When you hit 5+ Attributes, the karma to buy and raise a skill becomes cost prohibitive.

-Siege

using my nifty spreadsheet here are some examples

skill 1 vs TN 4 = 50% of getting one success
default at +4 you would need at least 4 dice to make better than the skill
skill 2 vs tn 4 = 75% default at +4 would need 8 dice to be equally likely to get 1 success

so following that all at tn 4 with defaulting
1 skill = 4 default (.5 vs .5177)
2 skill = 8 default (.75 vs .7674)
3 skill = 12 default (.875 vs .8878)

all of these are likelyhood of one success

move initial tn up to 8 and the results are
1 skill = 3 default (.1389 vs .1775)
2 skill = 5 default (.2971 vs .3578)
3 skill = 6 default (.4193 vs .4424)
4 skill = 7 default (.5173 vs .5197)

-Mike R

this is only for one success so not a good measure for combat with staging.
edit: for clarity

here's the spreadsheet if anyone wants to check my work...

http://users3.ev1.net/~skywise/shadowrun-d...probability.xls

-Mike R.

Doing the math, An elf character with a Charisma of 8 will probably out-negotiate a character with skill 5 (probably scoee more 9s than the skill 5 scores 8s). With 9 Cha you will probably out-negotiate even a skill 6 character, although a skill 7 character will probably still beat you. You stand no chance against a skill 8 character, unless you have some bonuses from edges and stuff.

Fahr and Lilt, you are both forgetting that you can't default if the TN before defaulting penalties is 8 or higher.

Lilt, a negotiation roll has a TN of the other's Intelligence, not the other's skill. I don't think your results are correct.

actually If you look again, I did.

the first set of examples was vs. base tn 4, the second vs. base tn 8, i didn't include any higher as 8 is the highest you are aloud to default to.

-Mike R.

edit: oh I see, "8 or higher", not "higher than 8", my mistake...

Wow. I've been playing negotiations wrongly for a while now. I did not forget that you cannot default if the TN before penalties is 8 though.

Fahr: Are you sure that spreadsheet is correct? I'm guessing it's supposed to be probability (IE: multiply by 100 and you get percentage chance) but those numbers look far too kind. Since when was there a 50% chance of hitting TN 12 with 7 dice?

BTW: The proggy I use for all my shadowrun "What If..." calculations is the Shadowrun dice roll probability calculator. All it's missing is the ability to simulate multiple sets of rolls (Drain resistance, Spell resistance, Opposed checks and stuff) simultaniously...

I posted it so somwone could check my work, so No I am not certain it is correct.

I made this a while ago using a probability textbook, and my probability math is rusty so I can't even remember the correct formula...

-Mike R.

edit:
man I would love to see the code behind that.

OK, I worked out the math for defaulting to an Attribute. Results comparing expected number of successes for given numbers of dice.
** Base TN 4:
Skill 2 beats Attributes up to 7
Skill 3 beats Attributes up to 10
Skill 4 beats Attributes up to 14
Skill 5 matches Attribute 18
** Base TN 5
Skill 2 matches Attribute 6
Skill 3 matches Attribute 9
Skill 4 matches Attribute 12 and so on
** Base TN 6
Skill 2 matches Attribute 4
Skill 3 matches Attribute 6 and so on
** Base TN 7
Skill 2 matches Attribute 6
Skill 3 matches Attribute 9 and so on
** Base TN 8
Skill beats Attribute at all values

If you can add Combat Pool to your roll, then use twice your skill value in the above table to determine probability.

/Edit: My calculations are for expected number of successes, and Fahr's calculations are for probability of getting one or more successes. These are different things with different numbers.

Fahr: Your single die rolls look correct, there appear to be some errors in the 2nd column though as you get into the probabilities for the exploding D6.

Yeah, but they should get bonuses for dealing with Trolls and Orks -- or at least not suffer the same number of penalties.

Or do trolls think each other as offensive as it would seem everyone else does?

-Siege

OTOH: My next character is gonna take a troll fixer contact
And technically trolls dealing with trolls are somewhat even as they both have the intelligence penalty

Yeah i found this out when i created a troll NPC fixer. "Tn's 4 to get a better deal??!!, nope have a free Cerebral Booster Mr Jackson"

Strangly none of my player minded.