Some Traveller Economics

I've kind of got Traveller on my mind now.  I was looking in the encounter tables and saw that encountered police are always armed with revolvers.  I know that while many police departments use revolvers, many also use automatics, and then that got me to thinking that in some places and in certain circumstances, the police also use shotguns, submachine guns, and assault rifles, and there's really no reason that future cops in similar circumstances wouldn't use advanced combat rifles or some of the other higher tech level weapons in the game.  The most basic constraint on what the department uses is going to be its budget, and that is going to depend on how many taxpayers they have paying in and how much they pay in taxes.  So now I have to figure out some basic economics here.

There are listings for salaries of starship crew, and Mercenary has wages for all ranks of mercenary forces, but the best, most general indicator of the income of regular people in the Traveller game is the listing of food and lodging costs.  We can take the "starvation diet" and "dismal lodging" as the bare minimum you can pay without becoming homeless and hungry, and the "excellent" levels of food and lodging as the upper limit of actual quality increases, as opposed to conspicuous consumption.  This leaves two in-between levels of apparent middle class costs. 

Now, if you've studied statistics at all, you should know the difference between median and mean.  The median is what you get when you line up all your data points in order and find the one in the middle.  For incomes, the median is the point where half the population makes less and half makes more.  Mean is what you get when you add up all the incomes and divide by the population...per capita income, in other words.  When you're talking about incomes, the median will almost always be less than the mean, and will never be more.  This is pretty obvious if you think about it: the half of the population that makes more than the median income drives up the mean, and while the half making less than median income pulls it down, there's a lower limit to how low they can go and survive, whereas no one's survival is impacted by having too much money.  I propose we take the "reasonable diet" and "acceptable lodging" as the median, with the "good" levels as the mean.

Since we know how much is spent on food and lodging per capita, we can ballpark the total income.  In 1977, consumers (Americans at least) spent 25% of their income on food and 33% on housing.  Since "good" food and lodging both cost 200 Credits per month, we can see this doesn't map exactly.  To be honest, I'm not too surprised that Marc Miller didn't bother getting that far into the weeds on this, but I'm going to go with it anyway; he surely had some impression of how the economy was supposed to work just from living in it.  And I'm specifically using 1977, because using current costs would end up looking more like cyberpunk.  So, if 400 Cr/month is about 58% of the total income, then the total should be about 690 Cr...let's just call that 700 Cr/month as the mean.  For what it's worth, the median income (closer to what the average man on the street would be making) is just over 500.

I originally was going to work out an income distribution chart or something, to figure out how many people we had on any given planet or any given sector of space living in poverty, and how many living just above poverty, and so on, and then work out the size of the economy, but then I realized that since I already have the mean (per capita) income, I just need to multiply that by the number of people to get a GDP for that particular political division.

So, a planet with 10,000 people on it would have a monthly GDP of 7 million Credits, and if we assume that police departments take up 1% of GDP (which is about what they did in 1977), this planet's police would have a monthly budget of 70,000 Credits for salaries and equipment.  If they're paying their officers the mean income (and police do tend to make more than the median income), they could have somewhat less than 100 officers, depending exactly on what their costs are for equipment procurement and maintenance.  I'll give some more thought to what kind of costs that will entail and post about it later.

Population Density in Traveller

Poking through Classic Traveller Book 3, I found a section that has always kind of bothered me.  In discussing world generation, under population density it says "For comparison, the following population densities are common on twentieth century Earth.  Earth on the whole has a population of about three billion (population level 9), this is approximately 5 persons per square mile, or 16 persons per square mile of land area.  Europe is populated at about 151 person per square mile, the equivalent of population level 10.  The Netherlands contain 1500 persons per square mile, or about population level 11.  Hong Kong has 10,000 persons per square mile, the equivalent of population level 12."

Now, there are several reasons this bothers me.  First, imperial measurements don't really fit well with science fiction, in my opinion, unless we're talking about Victorian sci-fi, or Flash Gordon/Buck Rogers style pulp sci-fi.  All these measurements should be in metrics.  Second, population is determined by 2D-2, with no DMs, so there is no level 11 or 12.  But perhaps most importantly, the population score is represented elsewhere in Book 3, as well as later in Book 6, as a general population value and not a population density.  Therefore, a small planet would have a higher population density than a larger one with the same population score.  Furthermore, since people live primarily on land, planets with larger oceans will have higher population densities than desert planets, houseboats, platforms, and underwater domes notwithstanding.

So, in a fit of gamer ADD, I needed to do some fiddling around in general terms.  Nothing I've done here is really ground-breaking, but this kind of thing should be taken into account by Traveller GMs, or GMs of similar games like Stars Without Number.

First and foremost, on any planet where humans can't just hang out on the surface in street clothes, none of this applies.  If there's no atmosphere, not enough atmo, or a toxic atmo, all settlements will be built like space stations, with airlocks and air processing and not a whole lot of privacy.  In these situations, the economics of building safe habitations and providing appropriate life support will ensure relatively high population densities in settled areas, and wilderness everywhere else.  Similarly, on planets with 100% of the surface covered by water, settlements will be artificial structures, and economics will tend to ensure high population density (although if a water world has a nitrogen/oxygen atmosphere, a lot of people might opt to buy their own watercraft to live on and get away from the crush).  Those planets with breathable atmospheres have more options, though...high density city living, or a lonely cabin out in the sticks.

What I've done here is calculated out the approximate land area of different sized planets with different hydrographics ratings.  Since this is just a thumbnail sketch rather than a comprehensive rule system, I just went with default planet sizes (no variations from the standard) and default hydro ratings (ten percent increments).  I also did these calculations in square kilometers (!)

	hydrographic rating
world size	0	1	2	3	4	5	6	7	8	9
S	306K	na	na	na	na	na	na	na	na	na
1	7.65M	na	na	na	na	na	na	na	na	na
2	32.13M	28.92M	25.7M	22.49M	19.28M	16.07M	12.85M	9.64M	na	na
3	71.91M	64.72M	57.53M	50.34M	43.15M	35.96M	28.76M	21.57M	14.38M	na
4	127.5M	114.75M	102M	89.25M	76.5M	63.75M	51M	38.25M	25.5M	12.75M
5	199.41M	179.47M	159.53M	139.59M	119.65M	99.71M	79.76M	59.82M	39.88M	19.94M
6	287.13M	258.42M	229.7M	200.99M	172.28M	143.57M	114.85M	86.14M	57.43M	28.71M
7	390.66M	351.59M	312.53M	273.46M	234.4M	195.33M	156.26M	117.2M	78.13M	39.07M
8	510M	459M	408M	357M	306M	255M	204M	153M	102M	51M
9	645.66M	581.09M	516.53M	451.96M	387.4M	322.83M	258.26M	193.7M	129.13M	64.57M
A	797.13M	717.42M	637.7M	557.99M	478.28M	398.57M	318.85M	239.14M	159.42M	79.71M

This next table is barely of interest.  Just a rough estimate of people per square kilometer, based on population rating and a few benchmark planetary land areas.  Because population rating is just an estimate in the first place, I didn't bother getting into a whole lot of detail, and anyone who can divide by ten can easily recreate the table.  I also didn't bother working out numbers for less than 1 per sq km...it's basically all wilderness at that point.

	population rating
surface area	0	1	2	3	4	5	6	7	8	9	A
100K	0	0	0	0	0	1	10	100	1000	10K	100K
1M	0	0	0	0	0	0	1	10	100	1000	10K
10M	0	0	0	0	0	0	0	1	10	100	1000
100M	0	0	0	0	0	0	0	0	1	10	100
1G	0	0	0	0	0	0	0	0	0	1	10

So, finally, I looked up some representative countries with these approximate population densities.  At 0 (less than 1 really) we have Greenland...essentially small settlements in the most appropriate areas (most efficient resource exploitation, most comfortable weather, most scenic areas; you have a whole planet to pick from, so why not?) with the rest of the planet as uninhabited (possibly uninhabitable) wilderness.

At about 1 per square kilometer, there's Mongolia, with some decent sized cities and widespread, low-level habitation everywhere else (basically wilderness).

At about 10 per sq km is Russia; large cities and industrialized areas but still large unexploited wilderness areas.

At about 100 is Turkey (and most industrialized modern countries for that matter).  Cities, some sprawl, but still a lot of wild areas and low density agricultural areas as well.

At about 1000 people per square kilometer, we have Bangladesh.  Densely populated cities with some very tall buildings, cities and towns tend to blend seamlessly into each other, but there are still some rural areas punctuated by smaller cities and towns.  The Hawaiian island of Oahu has about this same level of density, if you've ever been there.

At about 10,000 people, our example is Singapore.  Once you start getting up this high, rural areas really get crowded out.  Lower levels of overall density have pockets of highly dense settlement, but it's getting pretty uncomfortable now; people spread out as much as possible.

The smallest planets with the highest populations can reach up to 100,000 people per square kilometer.  There are some places on Earth now with that level of population density, but they're not well known...basically some neighborhoods in some already densely populated cities.  I can only imagine a planet-wide version of this would be the Traveller equivalent of Coruscant, with city everywhere, and the only variation being how tall the buildings are.

And now that itch of mine is scratched.  More accurate population densities in Traveller's world generation.  I've been thinking about working up some system using Zipf's Law to figure out more detailed settlement patterns for science fiction games.  Whether I come up with anything worthwhile remains to be seen.  And of course, I can't seem to stay on task for almost anything anyway.  Today's post came about when I intended to work on another Patron for DCC.  We'll see what happens I guess.