PBG Generation Rules

[Gruffty the Hiver]

Population Multiplier
LBB 3 Worlds and Adventures: No rule for generating this.
LBB 6 Scouts: No rule for generating this.
MegaTraveller:

Population Multiplier
Roll 1D and determine if the result is odd or even.
If even, roll 1D-1 for a result from 0 to 4. Ignore and reroll a result of 5.
If odd, roll 1d+4 for a result from 5 to 9. Ignore and reroll a result of 10.

Thought: why not just go for a straight 2D-2 throw, ignore/reroll a result of 10?

Belts
LBB 3 Worlds and Adventures: No rule for generating this.
LBB 6 Scouts: Throw 6 or less on 2D for planetoid belts to be present in-system. Throw 2D on the Planetoid column of the System Features table (shown on p. 28, LBB 6 Scouts):

PLANETOID
---------
2D  Quantity
 0  3
 1  2
 2  2
 3  2
 4  2
 5  2
 6  2
 7  1
 8  1
 9  1
10  1
11  1
12  1

DM: minus the number of GGs already in the system.

MegaTraveller: MT flipped the 6 or less throw and made it an 8+ throw.

Roll 8+ on 2D to determine if planetoid belts exist in the system.
If planetoid belts exist, determine how many from the Planetoid Belt Quantity table.

PLANETOID BELT QUANTITY
-----------------------
2D  Quantity
 2  1
 3  1
 4  1
 5  1
 6  1
 7  1
 8  2
 9  2
10  2
11  2
12  2
13  3

(....don't ask me how you get a result of 13 from a straight 2D throw and no DMs :? .....)


Gas Giant Presence & Number
LBB 3 Worlds and Adventures: Throw 9 or less on 2D for GGs to be present in-system. No rule for determining how many GGs are present though.
LBB 6 Scouts: Throw 9 or less on 2D for GGs to be present in-system. Throw 2D on the Gas Giants column of the System Features table (shown on p. 28, LBB 6 Scouts):

GAS GIANT
---------
2D  Quantity
 1  1
 2  1
 3  1
 4  2
 5  2
 6  3
 7  3
 8  4
 9  4
10  4
11  5
12  5

(....don't ask me how you get a result of 1 from a straight 2D throw and no DMs :? .....)

MegaTraveller: MT flipped the 9 or less throw and made it a 5+ throw.

Gas Giants
Roll 5+ on 2D to determine if gas giants exist in the system. If gas giants exist, determine how many from the Gas Giant Quantity table.

GAS GIANT QUANTITY TABLE
------------------------
2D  Quantity
 2  1
 3  1
 4  2
 5  2
 6  3
 7  3
 8  4
 9  4
10  4
11  5
12  5

 

[Gruffty the Hiver]

So my [edited] thoughts on this:

Population Multiplier
Roll 1D and determine if the result is odd or even.
If the result is even, roll 1D-1 for a result from 0 to 4.
Ignore and reroll a result of 5.
If the result is odd, roll 1D+4 for a result from 5 to 9.
Ignore and reroll a result of 10.
Barren Planets: For a planet to be completely uninhabited (i.e. not one single sentient living there and to qualify for the Barren Trade Classification) the planet's Population code must be 0 and the Population mulitplier must also be 0.
Inhabited Planets: All planets that have at least one inhabitant must have a Population multiplier of at least 1.

Belts
Throw 8+ on 2D for planetoid belt(s) to be present in-system.
If planetoid belt(s) are present, throw 2D on the Planetoid Belt Quantity Table.

PLANETOID BELT QUANTITY TABLE
-----------------------------
2D  Quantity 
 2  1 
 3  1 
 4  1 
 5  1 
 6  1 
 7  2 
 8  2 
 9  2 
10  2 
11  2 
12  3

Gas Giants
Throw 5+ on 2D for gas giants to be present in-system.
If gas giants are present, throw 2D on the Gas Giants Quantity Table.

GAS GIANT QUANTITY TABLE 
------------------------ 
2D  Quantity 
 2  1 
 3  1 
 4  2 
 5  2 
 6  3 
 7  3 
 8  4 
 9  4 
10  4 
11  5 
12  5

 

[Gruffty the Hiver]

Sorted .............or so I thought .............

 

[SableWyvern]

2d6-2 does result in illogical clustering of results (why are populations clustered mainly around 10^n x 5?).

Short of using a d10 (which would be rather out of place in an otherwise entirely d6 system), the CT method does gives a better balance to the results. In the end, though, a 2d6 bell curve probably isn't that much of an issue.

 

[Border Reiver]

And TNE logically uses 1D10 for the pop. modifier and follows MT for the rest.

T4 conveniently ignores the whole issue but continues to use PBG codes. :? But in Pocket Empires it offers both the 1D10 TNE method and the MT method.
:lol:

Possibly worth sticking to the MT method?

 

[Gruffty the Hiver]

I dunno. Personally, I can't see the difference between the MT system and just chucking 2D and taking 2 off the result (although I fully agree that still gives a bell-curve of results).

Maybe C'pnJack could explain the difference between the MT way and just throwing 2D-2?

 

[EDG]

Well I just roll 1d9 for PBG, but I can do that with a computer

I guess rolling 1d10 and ignoring a 0 works though. I only let pop 0 worlds have 1-9 people if the pop roll is exactly 0 (not below it, in which case it's Barren). Though I'm finding that results in a large number of worlds that have 1-9 people, which seems daft to me.

 

[SableWyvern]

Statisically, the MT system is just a method of rolling 1d10 with a six sider -- it gives a perfectly linear result.

1d6-1, ignore a result of 5 gives an equal chance of rolling 0, 1, 2, 3 or 4 (you are rolling a d5 numbered 0-4, in effect)

1d6+4, ignore a result of 10 gives an equal chance of rolling 5, 6, 7, 8 or 9 (you are rolling a d5 numbered 5-9, in effect).

The initial roll gives an equal chance of the final result being in the upper or lower band. Thus, 50% of your rolls will be 0-4, and 50% 6-9. Just like if you simply rolled a d10.

Or, putting it another way, the chance of rolling any given number is determined as follows:

Chance you take the lower die = 50%
Chance you roll 1 on that die = 20%
Total chance of rolling 1 = .5 x .2 = 10%

Chance you take the lower die = 50%
Chance you roll 2 on that die = 20%
Total chance of rolling 2 = 10%

And so on, to get exactly equal probabilities for each one.

But, like I said, 2d6-2 is simpler, and who really cares about some slightly odd clustering that's not really going to effect anything?

 

[Gruffty the Hiver]

Well I just roll 1d9 for PBG, but I can do that with a computer

.....muttermuttermutter...smug g*t...muttermuttermutter.....

 

[AKAramis]

I dunno. Personally, I can't see the difference between the MT system and just chucking 2D and taking 2 off the result (although I fully agree that still gives a bell-curve of results).

Maybe C'pnJack could explain the difference between the MT way and just throwing 2D-2?

2d-2 plot (Grufty way)
0 *
1 **
2 ***
3 ****
4 *****
5 ******
6 *****
7 ****
8 ***
9 **
A *

1d then 1d plot, using MT method
0 ***
1 ***
2 ***
3 ***
4 ***
5 ***
6 ***
7 ***
8 ***
9 ***
- ******

Note that the - result is a reroll required. Both have 36 entries plotted.

 

[Gruffty the Hiver]

Thanks for the clarification, Sable Wyvern and Aramis - that's helpful. Having seen the results of the two different methods, I'd go with the MT way, now

 

[captainjack23]

Maybe C'pnJack could explain the difference between the MT way and just throwing 2D-2?

Aramis has it very nicely correct -adding the count for the reroll is a nice touch.

As to why pop centers in the 10^5, I suspect it's an authors decision I'd assume that it was a n arbitrary result that drove the setting, but I know Marc was a socio-political guy..that may have given a good model for an 'average' population planet that worked-it approximates the population of one of the superpowers - in the 70's, anyway.

 

[EDG]

I'd guess Marc used 2d for population because those were the dice that Traveller was using originally - there's nothing in CT that uses d10s IIRC.


Question: For my CT UWP and tradecode generator, should I really be using Pop Multipliers at all? I guess I shouldn't really, since they were added later. So with book 6 rules, a pop 0 world really should mean "no people", which would mean that gov=0, law=0, and TL=0 as well (and also, the trade codes in CT should only count for worlds with pop 1+).

 

[captainjack23]

I'd guess Marc used 2d for population because those were the dice that Traveller was using originally - there's nothing in CT that uses d10s IIRC.

Ya think ?

Question: For my CT UWP and tradecode generator, should I really be using Pop Multipliers at all? I guess I shouldn't really, since they were added later. So with book 6 rules, a pop 0 world really should mean "no people", which would mean that gov=0, law=0, and TL=0 as well (and also, the trade codes in CT should only count for worlds with pop 1+).

Since you asked, no, you shouldn't. Are the 0=0 rules in MGT ? I think they were. In which case yes. As to the trade code, I'd also say no until we hear from Gar that he's changing it. Unless you want to generate your own data, which is cool. Just label it, so no-one thinks you're salting it.

 

[SableWyvern]

Just to be clear, when talking about clustering, I wasn't talking about the fact that the median population is in the 100,000s, but referring specifically to the effects of using 2d6 to determine the pop multiplier.

Doing so means that 5 is far more common than 1 or 9, 50 is more more common than 10 or 90, 500 is more common than 100 or 900 etc... You end up with a bell curve for population that is covered in little mini-bell-curve bumps.

For further clarity - a clustered population overall I have no problem with whatsoever.

 

[Knightsky]

Gas Giants
Throw 5+ on 2D for gas giants to be present in-system.
If gas giants are present, throw 2D on the Gas Giants Quantity Table.

GAS GIANT QUANTITY TABLE 
------------------------ 
2D  Quantity 
 2  1 
 3  1 
 4  2 
 5  2 
 6  3 
 7  3 
 8  4 
 9  4 
10  4 
11  5 
12  5

Would it screw things up too much to just roll a d6 for the number of gas giants?

 

[EDG]

Since you asked, no, you shouldn't. Are the 0=0 rules in MGT ? I think they were. In which case yes. As to the trade code, I'd also say no until we hear from Gar that he's changing it. Unless you want to generate your own data, which is cool. Just label it, so no-one thinks you're salting it.

Gar has said to use pop 1+ for the tradecodes for MGT (see http://www.mongoosepublishing.com/phpBB2/viewtopic.php?t=33041 ). I'm going to assume that's what should be done for CT as well since it shouldn't have pop multipliers either.

 

[Deniable]

Gar has said to use pop 1+ for the tradecodes for MGT (see http://www.mongoosepublishing.com/phpBB2/viewtopic.php?t=33041 ). I'm going to assume that's what should be done for CT as well since it shouldn't have pop multipliers either.

But the funny thing about Book 3 is that it goes both ways on 0 population.

Population: (2D-2) The digit indicating population is an exponent of 10. This may be viewed as the number of zeros following a one. Thus, a population digit of 5 indicates a population of approximately 1,000,000.

0 No Inhabitants

So it appears that Book 3 needs the multiplier to be consistent with one of its statements.

Later editions clarified population 0 as 0-9 inhabitants.

That being said, if MGT isn't using the population multiplier then code 0 almost has to be changed to mean uninhabited.

 

[captainjack23]

Gas Giants
Throw 5+ on 2D for gas giants to be present in-system.
If gas giants are present, throw 2D on the Gas Giants Quantity Table.

GAS GIANT QUANTITY TABLE 
------------------------ 
2D  Quantity 
 2  1 
 3  1 
 4  2 
 5  2 
 6  3 
 7  3 
 8  4 
 9  4 
10  4 
11  5 
12  5

Would it screw things up too much to just roll a d6 for the number of gas giants?

Well, other than changing the distribution, not really.

Given that Sol has 4, my only comment is that seems about right if you assume the earth and sol system are NOT an average world/system , but significantly different generally in the direction of "more" (size, Hyd, pop). (earth = 8, 3 sizes above average. , so ,say, 2.5 SD , which wonder of wonders is generally a significant difference)

 

[captainjack23]

Since you asked, no, you shouldn't. Are the 0=0 rules in MGT ? I think they were. In which case yes. As to the trade code, I'd also say no until we hear from Gar that he's changing it. Unless you want to generate your own data, which is cool. Just label it, so no-one thinks you're salting it.

Gar has said to use pop 1+ for the tradecodes for MGT (see http://www.mongoosepublishing.com/phpBB2/viewtopic.php?t=33041 ). I'm going to assume that's what should be done for CT as well since it shouldn't have pop multipliers either.

I guess that's what he meant...I thought initially he was just commenting on the Ba code, but on second read (& thought), since ALL pop 0 worlds are barren, then she says clearlY they have no trade codes. Yes ! An official clarification.

That said, still no word on the 0=0 set of rules ?