# The Premises of Traveller: 3. Most Worlds are Unimportant

So a question - what is the mean population and TL an Imperial citizen is born to on average, and what is within 1 standard deviation.

So a question - what is the mean population and TL an Imperial citizen is born to on average, and what is within 1 standard deviation.
That's question I've thought about. The Population part is easy from the default rules, as computed above: Pop 9. This might be conceptually hard to understand until you think of all the citizens of the Imperium lined up and you pick one at random, most of them are from Pop 8-A worlds. Note that the mean WORLD is Pop 5, not the same as the mean citizen. TL is harder because of all the dependencies. A direct calculation is possible but complicated, so a simulation would be best, I and haven't done one yet. Has anyone?

P.S. A first pass at the modal TL (single most common value) is TL 7-8 (1D = 3-4 +2 (C starport) +1 (Pop 5) +1 (Gov 5)). This is using CT rules and assumes all 7s are rolled for 2D. But this may not be quite right, again given dependencies.

Intuitively, I'd guess any central tendency measure is skewed up by the Starport DMs (+6 for Class A, +4 for Class B) and Population (+4 for A, +2 for 9). It wouldn't surprise me if the actual mean were closer to TL 9-10, Early Stellar.

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OK, I did the simulation of TL. 1040 values. Much less skew than I thought, nearly a bell curve. So the average/median/mode are all TL 8.

TL 8 is a bit of surprise average. I image a far future setting to be on average further along in TL progression.

On the other hand, this seems to suggest that there is a fair volume of decreasing TL worlds to accompany all of the general TL progression. I imagine that disasters of various sorts drive down tech levels perhaps showing the 3I known space to be fairly volatile.

TL 8 is a bit of surprise average. I image a far future setting to be on average further along in TL progression.

On the other hand, this seems to suggest that there is a fair volume of decreasing TL worlds to accompany all of the general TL progression. I imagine that disasters of various sorts drive down tech levels perhaps showing the 3I known space to be fairly volatile.

According to published sources concerning the OTU, in 1105 the Imperium is supposed to be an average of TL ~11-12.

"According to published sources concerning the OTU, in 1105 the Imperium is supposed to be an average of TL ~11-12."

OK, Math. The Pop roll is unconditioned by any other roll (i.e. no other rolls affect it). Thus, we can recompute the Pop TL DM by conditioning however we want. For example, the unconditioned Pop TL DM is +1. Conditioned on Pop>7 (99.6% of total population) the TL DM is +2. So we gain +1 TL simply by concentrating on Pop>7, and for just Pop 10 (+4 TL DM) the average TL is 11.

Similarly, the Starport is unconditioned by any other roll, but IS conditioned on the region of space. I used the standard formula, which has an average Starport TL DM of about +2.5. If we switch to a Cluster region, the DM increases to +3.5 or so.

In other words, in world/population dense regions of space (i.e. the Core Systems, where most sophonts), average TL IS closer to 11-12. This implies that Backwater/Low Pop regions would have much lower average TL. Sounds like the right feel to me.

Finally, I ran this simulation on the standard way to generate a main world. That has nothing to do with the official published Third Imperium, which if we could analyze that empirical could indeed have average TL of 11-12 simply owing to the choices made by the designers.

Similarly, the Starport is unconditioned by any other roll,
Actually, it is by Pop.
DM+1 if the planet’s Population is 8-9​
DM+2 if the planet’s Population is 10+​
DM–1 if the planet’s Population is 3-4​
DM–2 if the planet’s Population is 2–​
(Core, revised p. 257)​

Which further skews up TL of High Population worlds.

"Actually, it is by Pop."

Ah, I was wondering about that. I'm using MegaT rules, which are pretty close to CT rules. But yes, your conclusion is correct and increases the TL differences between core/frontier worlds even more.

To be fair, most of Charted Space - at least the Imperial space part, was likely done with a straight roll for Starport.

Umm, that's the way it was done in Traveller until Mongoose changed it.

OK, I did the simulation of TL. 1040 values. Much less skew than I thought, nearly a bell curve. So the average/median/mode are all TL 8.

View attachment 1576
Too few samples for the distribution to quite settle. You should not have a dip at TL 7.

As hi-pop is correlated hi-tech the average over pop is higher.

I get average over random worlds to about TL 8.2, same as you.
But average over population is about TL 10.5.
(I capped TL to 15 by old habit.)

The Imperium is not made from only random data, over the Imperial population the average is TL 12.1

"The Imperium is not made from only random data, over the Imperial population the average is TL 12.1"

Yes, this was noted above.

Published data isn't random.

By TravellerMap over the entire Imperium:
World size by # of worlds and by population compared to random distribution:

World atmosphere by # of worlds and by population compared to random distribution:

"The Imperium is not made from only random data, over the Imperial population the average is TL 12.1"

Yes, this was noted above.
Yes, but I didn't guess, I counted...

Yes, but I didn't guess, I counted...
Hey, thanks for posting those graphs! Interesting to see.

Published data isn't random.

By TravellerMap over the entire Imperium:
World size by # of worlds and by population compared to random distribution:
View attachment 1577

World atmosphere by # of worlds and by population compared to random distribution:
View attachment 1578
I think Don McKinney is responsible for the big increase in Size 5 worlds and the underrepresentation of Sizes 1-4, at least in the Spinward Marches. The original sector (and CT rules) doesn't seem to have had a negative atmosphere DM for Size 1 worlds, so I think he upped the size of those small worlds with actual atmospheres. Doesn't break the trade codes if you do that.

I think Don McKinney is responsible for the big increase in Size 5 worlds and the underrepresentation of Sizes 1-4, at least in the Spinward Marches. The original sector (and CT rules) doesn't seem to have had a negative atmosphere DM for Size 1 worlds, so I think he upped the size of those small worlds with actual atmospheres. Doesn't break the trade codes if you do that.
If so, that's very official sounding. I like weird atmospheres, as they are usually easy to protect against, but they allow for other alien weirdness, like creatures that process exotic atmospheres and then spew them out as defenses. Or taints that aren't deadly, but are narcotic, or stimulating, etc.

There is a lot of manipulation of the data going on.

Population is clearly shifted to size 7-8 and non-tainted atmospheres.
Lots of manipulation of size 0 belts too.

The graphs are for the entire Imperium, so the manipulation is pervasive.

Lots of manipulation of size 0 belts too.
Well, there is an in-universe reason for the Marches to have more asteroid belts than your average bear.

There is a lot of manipulation of the data going on.

Population is clearly shifted to size 7-8 and non-tainted atmospheres.
Lots of manipulation of size 0 belts too.

The graphs are for the entire Imperium, so the manipulation is pervasive.
Well, it is essential if you are trying to portray the an actual settled area. I can't speak for the game designers, but it sure looks like intent of the generation rules was not to reflect reality but to create a plausible frontier area suitable for pulpy sci fi adventure. Which it does pretty well, though obviously what's plausible is different today than 45 years ago

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