《可持续发展的时代》旨在让你了解可持续发展 所面临的关键挑战和实践途径 即兼顾社会包容性和环境可持续性的经济发展
Incomes Around the World
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來自 Columbia University 的課程
可持续发展的时代
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從本節課中
Inequality Around the World
Professor Sachs delves into the reasons for and the measurements of inequality between and within countries.
與講師見面
Jeffrey Sachs
Director, Earth Institute; Quetelet Professor of Sustainable Development; Professor of Health Policy and Management
[MUSIC]
Sustainable development, we've seen, has three major aspects,
economic development, broad-based inclusion, and
environmental sustainability, all supported by good governance.
But what do we mean by economic development?
I want to introduce the main concept of how we measure economic development.
Of course, there are many different aspects of a true and proper understanding
of economic development, Bbt we tend to use a shorthand, and
that is called the gross domestic product of a country.
The gross domestic product has three words and three concepts in it.
It means the total production taking place within the geographic
boundaries of a country in a given year, so the gross of the gross domestic
product means you're measuring everything that is taking place within the country.
You're not taking into account
in that measurement the depreciation of capital and so forth,
which would give us a different concept called net domestic product.
Domestic signifies that fact that we're talking about a geographic area,
and we're concerned with how much economic activity or
production takes place within the boundaries.
Of course, usually we're talking about a country, but
we could be talking about the production of a city or a region,
and sometimes, of course, we also want to talk about the gross world product,
which is adding up the domestic production across all of the countries of the world.
And product, or production, signifies the fact that what we're interested in
measuring is not the accumulated wealth, the wonderful buildings and
monuments and roads and infrastructure, the natural beauty of a country,
which may tremendously raise the quality of life.
We're interested in the actual flow of production in a given time period.
Now, for most purposes we look at a year.
Though, when policy makers are trying to understand short-term dynamics
of unemployment and production, they're interested often in measuring
the gross domestic product, even over a quarter of a year.
We're going to look at national measurement for countries.
We're going to look at the annual measurement.
Now, one more critical point about measuring the gross domestic product.
In general,
we're interested in getting a sense of the standard of living of a country.
And to do that, we take the total production in the country over a given
time period, usually the year, and divide it by the population, so that
we're interested in the gross domestic product per person, or per capita.
Why is that?
Well, of course, larger countries produce more,
because there are more people, there are more workers.
But if we simply were to compare countries in terms of the total production,
we'd find that highly populous countries would have higher production,
but we wouldn't learn very much about whether the living standards of those
larger countries is really higher then the living standards of a small country which
may produce a little bit, but quite a bit for each person in the economy.
So when we think about economic development,
we tend to think about the gross domestic product per person.
Let me emphasize again that's not really a comprehensive
measure of economic development.
We want to know whether people are healthy or not.
We want to know levels of education.
We want to know other indicators of well-being.
But as a shorthand, when I want to get a sense
of a country's overall level of economic development,
I start by looking at the gross domestic product per person,
because that's going to be a pretty good indicator of where things stand.
And indeed, that's what the keeper of the accounts, which is the World Bank, does.
The World Bank keeps very systematic tabulations
on gross domestic product per person, and
it classifies countries in a way that is also extremely helpful for us.
The World Bank gives three categories of countries.
High income countries, middle income countries, and low income countries.
And it puts each nation into one of those three bins,
depending on its measured gross domestic product per person.
Roughly speaking, a low income country is a country where
the domestic production per person is at a level
below a threshold of about $1,000 per person per year.
In other words, roughly $3 per day.
And a middle income country is a country is in a band
between $1,000, roughly, per person and
about $12,000 per person per year.
And the high income countries are countries that are above
the $12,000 per person threshold.
There are then refinements.
The middle income group, which is quite a big one,
is divided between the upper middle income and the lower middle income,
with a dividing line of about $4,000 per person, per year.
In the World Bank, categories provide us with a useful depiction,
a good map of the world, and if you look at the map in front of you,
you can see that those few areas that are shaded blue are the high income countries.
The U.S. and Canada, Western Europe, Japan and Korea,
Australia and New Zealand, and a few other parts of the world.
Add up the population of that high income group, and you find that it's
about 1 billion of the roughly 7 billion people on the planet.
So it's about one in seven in the world, roughly 15% of
the world's population, living in high income countries.
Then take a look at this large middle group
of beige colors.
And you'll see that covers a wide expanse of the world.
And indeed, five out of seven in the world's population, roughly 5 billion
of the 7 billion people on the planet, are in the middle income category.
So that's a big middle.
And that's divided between an upper part and a lower part, roughly half and half.
Approximately 2.5 billion people in the upper middle income category,
and about 2.5 billion people in the lower middle income.
Then look at the countries shaded red.
Those are the poor countries.
The low income category.
And by simple arithmetic, we can say that 7 billion minus the 1 in the high income,
minus the 5 in the middle income, that leaves about 1 billion people,
approximately, living in the low income countries.
We've already noted that the low income countries are heavily concentrated i
tropical Africa and in south Asia,
with a scattering of low-income countries in other parts of the world.
But in our world today,
the poorest countries in the world are concentrated in these two regions.
And most of the world's poor people, therefore,
live in those regions where the countries are in the low income category.
Now, let me mention one more category.
It's not a World Bank category, it's a United Nations category, but
also very important for us to remember.
Even within the low income countries, there are distinctions.
There is a subgroup within the low-income countries
that's in pretty desperate shape.
Not only are they poor, but the human conditions of disease,
of education levels, of social instability, are very bad.
And moreover, this subset of countries is highly vulnerable to droughts,
to floods, to conflict, to violence.
So these are a group of highly vulnerable, very poor countries,
and the UN has classified them as the least developed countries.
There are about 50, right now the list is 48, but
it goes up and down depending on how countries are performing.
Among the least developed countries, the poorest of those
are again heavily concentrated, you see that in tropical Africa,
there's a large number of least developed countries.
There are several in Asia, and
if you look closely at the map, you'll notice something very telling for us.
Afghanistan, Nepal, Bhutan, Laos, landlocked countries.
This is not by accident.
We're going to see that economic development
depends on international trade.
Being landlocked is a problem.
You'll also notice a number of small island economies in the Pacific and
also Haiti.
Small island economies also can be quite vulnerable and
part of the least developed countries.
We know what these categories look like intuitively.
It's good to remember London, and
my own hometown New York City, among the high income countries.
Middle income countries, Rio or
Sampaio in Brazil, where you have a tremendous amount of development and
wealth but you also have the favelas, the slums.
Countries that are in the middle
of the pack often doing very well in raising income levels.
China, another major world economy that is a middle income country.
The poor countries, we know what they look like, also, because they're more rural.
Small holder farmers, peasant farmers scratching out a living,
hardly making ends meet, and for the least developed countries,
Somalia, unfortunately, in its tragedy in recent decades,
really a clear example of what it means to be among the poorest of the poor.
And not only desperate poverty, hunger, lack of education,
low life expectancy, but lots of violence and lots of political instability as well.
Let me mention one more important detail for us, in terms of measurement.
For everything that I've said so far in measuring the gross domestic product,
the total production is added up and
divided by population to get the gross domestic product per person.
And since countries have their own currencies,
they have to be converted to a common standard.
So, the exchange rate is used to convert the national currency into a common,
typically US dollar, standard.
And that's how we make the comparisons in a common currency.
But there's another translation that can also be useful.
I want you to be aware of it, because we will be referring to it many times.
And that is to make one more adjustment for
the difference of costs or prices in different countries.
If you buy an automobile or a television set almost anywhere in the world,
the price will be fairly similar because these are goods that are traded
internationally, and
they have a similar price when expressed in dollars in any part of the world.
But if you go to rent an apartment or get a haircut or
go to a movie or park a vehicle in the center of town,
you'll find the difference in costs extraordinary in London,
or New York, or Tokyo, or Paris.
The prices would be sky high.
But, in a poor setting in Mogadishu, or in Accra or
in Bamako, Mali, the price of a hair cut might be a 20th or
a 50th of what you'd pay at a salon in Paris.
So one has to take into account that simply measuring the output and
converting to dollars might not give a full comparison, because the purchasing
power in a poor country might be a little bit higher than is indicated.
So we often make one more adjustment called purchasing power adjustment,
or purchasing power parity to take into account the relative price levels.
When you do that, you find that poor countries are still quite poor, but
they're not quite as poor as they look.
Take a case of a country like Malawi, a poor country,
landlocked in tropical Africa.
Measured in the market prices and the market exchange rate,
its per capita income is around $250 per person per year,
compared with $50,000 per person per year in the United States.
Malawi's extraordinarily poor.
Adjust for the lower costs of living in Malawi, and
you find that Malawi is still very poor.
But maybe the income with the purchasing power adjustment
should be around 900 to $1,000,
roughly four times higher than simply using the market prices.
So that's a system called purchasing power parity,
measures of gross domestic product per person.
It's a lot of words.
It's a lot of concepts.
The main point that I am stressing is that we measure
economic development in shorthand by the gross domestic product per person.
We adjust, obviously, for population, we adjust for currency, and
very often we want to adjust for the different price levels.
Then we can classify countries, and we can study the question,
why are countries at different levels of development?
How do those different levels of development relate to other things that
matter a lot for people, their health, their well-being, their happiness?
And what can countries do that are at the low end of this curve, the least developed
countries and the low income countries, to raise their living standards?
To achieve economic growth that is a rise of gross domestic product per person,
fast enough to narrow the gap significantly with the wealthier and
the hire income countries?
That, of course, is one of the key challenges of sustainable development.
