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>> "rate" means per capita per year.

>That's by no means the only meaning of "rate".

It is the standard definition when talking about a CRIME rate. Googling "define crime rate" returns things like this:

"the ratio of crimes in an area to the population of that area; expressed per 1000 population per year" http://wordnetweb.princeton.edu/perl/webwn?s=crime%20rate

A "murder rate", being a fair bit smaller, is almost always expressed per 100,000 people per year.

> If the population is increasing without constraint

It isn't. Population growth rates have rapidly declined all over the world. The US population would already be shrinking were it not for immigration. Even Bangladesh and India are currently reproducing at right around replacement levels.




> It is the standard definition when talking about a CRIME rate.

That wasn't your claim, and it's false in any case. There's no standard definition of "rate" -- you need to define your terms, and "rate" means a measure of change, not any specific measure without additional information. In any case, the exchange below tells me that you really don't understand what "rate" means.

>> If the population is increasing without constraint

> It isn't. Population growth rates [emphasis added] have rapidly declined all over the world.

Honestly. I say population is increasing. You reply by saying that the "growth rate", i.e. the first derivative of population, has declined. Both are true. To sort this out, take Calculus. Until you understand the difference between a function and its first derivative, we won't be able to discuss this issue.

http://www.arachnoid.com/calculus/

Also, for the actual worldwide population growth rate:

http://en.wikipedia.org/wiki/Population_growth

"In 2009, the estimated annual growth rate was 1.1%."

That rate, if sustained, means the world's population will double in 63 years.


> Honestly. I say population is increasing.

No. What you said was that population was increasing without constraint. It's that last bit I was responding to.

The fact that the rate of growth is declining does suggest the presence of one or more constraints, even if the overall growth rate hasn't quite reversed just yet. The primary form of the constraint appears to be that as childhood survival rates and living standards improve, families voluntarily choose to have fewer kids. This is happening all over the world, there's no reason to think it will stop any time soon, and it argues against your implication that "mass death" is the only likely way out.

(For what it's worth, I have taken calculus. And if you're the guy who wrote AppleWriter: Nice job! I liked that program. I used it in high school.)


> What you said was that population was increasing without constraint.

And that's correct -- any population increase above zero is without constraint. All one need do is calculate the doubling time:

http://arachnoid.com/lutusp/populati.html

> The fact that the rate of growth is declining does suggest the presence of one or more constraints ...

Yes, or more likely, it's a random fluctuation indicative of nothing in particular. The latter assumption, which may seem overly skeptical, is how a scientist is expected to look at an unexplained change in the rate, based on a precept called the null hypothesis -- a presumption that (in a manner of speaking) it's all random and meaningless.

> ... and it argues against your implication that "mass death" is the only likely way out.

Not really. Remember that nature efficiently picks out those with the highest birthrates and makes them the entire future population. My point is that population growth is naturally unstable, depending only on food sources and a willingness to push other species out of the way.

1.1% per annum may not seem like a very large rate of increase, but 63 years doesn't seem like a very long time to double the world's population either.

Exponential increases of all kinds are rather scary to model. They're scary enough when one looks at compound interest and how that naturally creates a chasm between rich and poor over time, but the "big show" for exponential increases is population, where much more is at stake.

> For what it's worth, I have taken calculus.

Okay, glad to hear it. Given that, I think you will appreciate what I thought when I heard you object that population couldn't be increasing because the rate of increase was decreasing.

> And if you're the guy who wrote AppleWriter: Nice job! I liked that program. I used it in high school.

Yes, that's me. Thanks.


>Yes, or more likely, it's a random fluctuation indicative of nothing in particular. The latter assumption, which may seem overly skeptical, is how a scientist is expected to look at an unexplained change in the rate, based on a precept called the null hypothesis

It's NOT UNEXPLAINED and it's NOT RANDOM.

Does your browser support Flash? If I point you at a chart composed using gapminder.org could you please please LOOK AT IT? (Or if you can't, could you let me know what the constraints are on what your browser can see, so I can find another way to get you the information?) The link will follow this paragraph. Press the "play" button below this chart to see an animated plot of fertility versus child mortality. Several specific countries are hilighted - you see a trail of their progress over time - but the ENTIRE MASS of countries follows much the same pattern - it moves down and to the left. Here's the link:

http://www.bit.ly/18hUMjA

It truly boggles my mind that you could think even for a second that the slowdown in population growth is "likely a random fluctuation indicative of nothing in particular". It is a TREND. The phenomenon is quite consistent. Across the ENTIRE PLANET, countries are increasing their GDP, decreasing child mortality and decreasing the rate at which they have kids, with all those changes roughly in tandem. And it's not a random walk where one needs to cherry-pick any specific interval to see these trends - if you just look at the entirety of ALL the data we have available and plot it, you can see a consistent movement.

Please look at the animation. Play around with it - use the checkbox list on the right to highlight other specific countries. Get a sense of what the data is actually DOING before you claim it's a random fluctuation.

A random walk WOULD be susceptible to cherry-picking - the trend would only show up if you pick certain time ranges or certain sets of countries.

This is not that.

(Given current trends, the world population would not double again - it would stop growing short of that.)




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