A lot of attention (myself included) has been recently put on the Top 1% income and wealth. However, there is also substantial inequality in the other 99% that is worth exploring. To get an idea, if we took all the Top 1% income growth between 1979 and 2012 and distributed it among the other 99%, each of us (I assume you also belong to the other 99%...) would earn around $7000. However, the increase in the earnings gap between a college-educated and a high-school educated household is four times that in the same period. Hence, here we will focus on wage inequality among the other 99%, but particularly between the bottom 10% and top 90%, so as to exclude the very extreme cases (which deserve a different attention). But first, Figure 1 shows how wages have changed between 1963 and 2005 by wage percentile. Here we see that generally there was a much bigger increase in wages among the top half than the bottom one.
Figure 1: Change in real wages by percentile, 1963-2005.
A common measure for overall inequality is the ratio of those at the 90 and 10 percentiles. A typical issue is that the population might be changing its structure, with more people getting educated or more work experience. As this happens, the typical person in either of these percentiles might be changing, hence changing our standard interpretation of increasing inequality. Another take on inequality is to look at between-groups inequality, where the typical comparison is those with a college degree and those with a High School degree. This tries to avoid the issues of other characteristics of the population changing as in the overall inequality measure. However, another alternative look at inequality is to look within-groups, hence evaluating how much variation there is among small groups (for example: college educated, 25-30 years old, male). This three measures of inequality are displayed in Figure 2, where we see that even though the three of them have increased over the long haul, they have done so at different paces and through different paths. Particularly the college premium follows a strange path, increasing in the 1960s, decreasing in the 1970s and increasing very fast since the 1980s. This suggests that a simple, unique explanation for the recent increase in inequality is not likely to work.
Figure 2: Three measures of Income Inequality.
But has inequality changed more among the top or the bottom? An easy way to look at this is to compare the 90 and 50 percentiles (upper-tail inequality) and, separately, the 50 and 10 percentiles (lower-tail inequality). Note this still excludes the very bottom and very top. Figure 3 shows that even though lower-tail inequality grew in the 1980s, it has not grown since then. On the other hand, upper-tail inequality has increased continuously.
Figure 3: Upper- and Lower-Tail Inequality.
So what is behind this monumental increase in inequality? Identifying the cause of this change is very hard or probably impossible, but what we can do better is identify the proximate causes, meaning what seems to be closely associated with this change, even if we do not understand what led to the first thing. And this is where the skills of economists Autor, Katz and Kearney comes into play. They argue that we cannot simply think of people as belonging to one of two groups - skilled and unskilled - where the top one is associated with higher education. Figure 4 shows that from 1979 to 2005 the wages of those with a post-college education grew by a lot more than those with college degree. Moreover, the difference between those with exactly college and high-school degrees slowed down significantly since the 1980s. And finally, the difference between those with high school degrees and those without one has flattened or even decreased since the mid-1990s. All this suggests that, since the 1990s we are in a situation where the income among the very high- and very low-skilled workers has increased relative to those in the middle. Income has polarized.
Figure 4: Changes in wages by Education.
What explains this? The main hypothesis is that computerization has changed the demand for job tasks and affected the demand for skills in such a way that explains this polarization of income. Computers are good at doing routine tasks which are codifiable, like bookkeeping, clerical work or repetitive production tasks. (If you have interacted with a call-center lately, you will probably know how computers have improved in voice recognition and seem to have taken over those tasks that require gathering the same information all the time). On the other hand, abstract tasks like those performed by "high-skills" managers or educated professionals are hard to automatize since they require cognitive and interpersonal skills and adaptability. Similarly, manual tasks used in many "low-skilled" jobs like security guards, cleaners and servers are hard to computerize and hence have not been affected much by the advance of computers. Figure 5 confirms this intuition that low-skill jobs (taking the average education of those performing such jobs) usually have manual tasks. On the other end, high-skill jobs are mainly filled with abstract tasks. However, routine tasks are concentrated between the 20th and 60th percentiles.
Figure 5: Task intensity by Occupational Skill.
The conclusion is that the change in wage inequality may be substantially explained by changes in the demand of skills, which has been lately polarized by the introduction of computers. As the demand for these jobs increased, so did their wages. But why haven't workers matched the increase in demand by educating themselves more? Well, most likely this change was very hard to predict and so not enough people found higher-education to be "worth it." However, recent trends in education attainment suggest that young people are catching up to this increased demand.
Based on an article by Autor, Katz and Kearney.
Figure 1: Live First-Birth Rates by Age of Mothers
The 1960s were revolutionary times. As Bob Dylan - one of my favorite musicians and probably one of the most famous characters of that time - said, "there is nothing so stable as change". This was certainly true in the US at the time: The Civil Rights Movements, social unrest due to the Vietnam War, the invention of the microchip, antidiscrimination legislation, the women's movement. And the invention of Enovid, the first contraceptive pill. Yes, you read right. The contraceptive pill was a revolutionary element. And as such, it has also been studied by an economist (and by the way published in the Quarterly Journal of Economics, among the top 3 economics journals). Martha Bailey evaluated the effect the release of this little pill in 1960 had on female labor participation. Gary Becker had previously said that "the contraceptive revolution [...] has probably not been a major cause of the sharp drop in fertility". However, Bailey will show that even if fertility did not decrease because of the pill, it did delay it, allowing women to get more education and improve their labor outcomes.
Figure 1 shows trends in first-birth rates by age groups since 1940. A marked decline in childbearing among young women (focus on 20-24 years old) is seen since the pill was introduced. This lasted until 1976 when all unmarried minors were allowed obtain contraceptives under the law. Early access allowed women between 18 and 21 to get access to the pill and hence the largest decline is seen for those 18-19 years old. A first robustness check can be seen from those 15-17 years old. Since they are expected to be too young to benefit from the pill, we should and do observe no effect for them. This gives us confidence we are not just seeing a spurious result.
As the diffusion of the pill increases, the distribution of age at first-birth also changes. Figure 2 plots the fraction of women first giving birth by age groups and cohorts. Among women born before the 1940 who were too old to benefit from early access to the pill, around 62% report having children before age 22. For those born around 1955, this had dropped by 25%. Notice that both figures suggest that these effects were not due to preexisting trends. Also no changes are seen between 1955 and 1960, when all women would have already had access to the pill.
Figure 2: Distribution of Age at First-Birth, by Cohorts.
And where does the economics come in? Early access to the pill was reflected in female labor force participation. Before 1940 the increase in women's participation had been driven by married women over 30 years old, who returned after their children had grown. On the other hand, for those born in 1955 the "fertility dip" is not observed any more. Participation rates were 25% higher at age 25.
Figure 3: Labor Force Participation, by Age and Cohort.
But how can we disentangle the effect of the pill from all the other things going on the 1960s that I mentioned above? Here is were econometric tools come in. The expansion of the pill was different across states, which individually changed the legal rights of individuals ages 18 to 21. Indirectly, this effect empowered women to get early access to the pill, without parental consent.* This exogenous variation will allow Bailey to compare the effect of the pill on women's life cycle labor force participation. Just to fix ideas, the methodology is like taking two states that were previously equal. But one state decides to extend legal rights to younger individuals and the other does not. Consequently, only one state allows young women to get access to the pill. Then, the difference in the labor force participation of the women between the two states will be coming from the pill. More than two states and more controls are used to obtain the results, but the intuition of the technique is in the previous simple example.
A first thing to check is whether early access to the pill had an effect on fertility. Table 1 shows the baseline estimate (column 2) is that it reduced the probability of giving birth by age 22 by 14%. Interestingly, early access to abortion does not seem to drive the results (column 3). As expected, it did not reduce the number of children before 19, since women did not have legal access to the pill without parent consent before that age. Finally, as other people had reported, the pill did not reduce the number of children women had, suggesting it just delayed it.
Table 1: The effect of early legal access to the pill on fertility.
What effect did this have on labor outcomes? Bailey shows that early access to the pill increased labor force participation of women ages 26-30 by 7%, and also increased those of ages 31-35. They also seem to work more hours, hence getting closer to male labor outcome averages. For women under 25 years old, results suggest that the pill increased their enrollment in school. Changing career trajectories - resulting from delay in childbearing - was the primary mechanism this little pill increased female labor-force participation.
* Bailey goes into some detail to justify that this extension of rights was not related to states characteristics that could be directly related to the variables of interest. Most of the changes are suggested to have to do with discrepancy under federal law of being old enough to be drafted to the Vietnam war by age 18, but not being able to vote. At the state-level, legislation was extending rights to 18 year old men and women.
Figure 1: Composition of US Income Inequality.
In the last few years, substantial research from Piketty, Saez, Atkinson and others has brought the topic of inequality back to the front page of economics. They use extensive data, including tax records in some cases, to analyze the evolution of (mainly top) income inequality for a long period of time. Charles Jones has updated and summarized some these studies, which is the basis of this article. The starting question is then: How much inequality is there?
Figure 1 shows the share (and composition) of income held by the top 0.1% of the population. The first striking finding is that there is a long U-shaped pattern: (Top) Inequality was very high before the Great Depression (with the top 0.1% holding as much as 10% of the total income); Lower and steady inequality after WWII; Rising inequality since the 1970s (reaching pre-1930 levels).
Taking into account that GDP can be theoretically split into labor income (e.g. wages, salaries and business income) and capital income (capital income and gains), we can divide the analysis of inequality in a similar fashion. This shows that most of the initial decline is due to a reduction in capital income, while most of the sequential increase is due to labor income (and capital gains possibly). The returns on capital seem to have become relatively smaller for the top 0.1% of the population, while wages and business income have become more important. (A big driver of of this might be the importance of land rents in the income of this part of the population)
If you have read about Piketty's book, you may have heard about the magnitude of wealth inequality. Wealth inequality is much greater than income inequality. While the top 1% of the population hold about 17% of income, the share of wealth held by them in the US is estimated to be above 40%. The cutoff to be in the top 1% of income is 330 thousand dollars a year, while 4 million dollars are needed to be among the wealthiest 1%. Figure 2 shows the path of wealth inequality for the France, the US and the UK. It is seen that wealth inequality was a lot higher before WWI than it is today. However, this hides the fact that wealth inequality has started to increase in the 1960s. On the positive side, (at least for UK and France) it still remains smaller than in the 19th century.
Figure 2: Wealth Inequality.
So far we have discussed how inequality has behaved within labor income and within wealth. Given the importance of inequality within wealth, the remaining question is how has the share of income taken by capital evolved over time. Since most of the capital income is captured by a small number of people, a tiny change in the share taken by capital (instead of labor) can lead to substantial effects on general levels of inequality. While most of the previous plots focused on the top 1%, this is now more about the top 10% (which holds 3/4 of the wealth in the US) versus the bottom 90% (which holds the other quarter, most of which is actually held within the 50-90% range). Figure 3 shows that the share of income taken by capital had either decreased or remained stable until the 1980s. However, since then, the share of income (think of this as the share of the revenues taken by capital and property owners) taken by capital has increased in all three countries.
Figure 3: Capital share of payments.
Inequality is a big concern. However, its causes and consequences remain a puzzle. On the causation side, much research remains to be done. On the consequences side, many views are possible. Regarding the individual level, inequality might affect the chances some people have of making progress, for example through access to education. If children lack basic needs (like food), they most likely won't attend school. Regarding the aggregate level, inequality might also hinder general economic growth. For example, through reduced access to education, innovation might be damaged. However, it has also been claimed that inequality might be necessary for growth. For example, in a very poor country, if wealth is split equally no one might be able to invest. However, higher inequality might allow the richest people to be able to use their extra resources to invest and generate growth. Later, opportunities for the poor ones might flourish, leading to lower inequality. This is known as the Kuznets curve. Whatever your hypothesis is, careful thinking and proper research are probably necessary.
Based on a working paper by Charles Jones.
How do individual labor earnings evolve over the course of a person's life? If you have ever asked yourself "Should I expect my income to increase this year?" and "By how much?" this post might interest you. In a very elegant study, Guvenen, Karahan, Ozkan and Song have tried to answer these questions and more, using over 200 million tax data observations from Social Security Administration (between 1978 and 2010). If you ever thought tax data was not public, this (and my last post) might suggest that they are not. Don't worry. Only a few people are allowed to use this information, and even then they are not allowed to actually see the name of the person behind each income observation.
Looking at employed people between the ages of 25 and 60, they focus on how much earnings grow every year in average. A first look at the data is provided in Figure 1. Taking the average among all the population, yearly income peaks around 50 years old, with an increase as high as 127% from age 25.
Figure 1: Average (Log) Earnings by Age.
If you are past age 50 and have not seen such an increase, you might be wondering what's wrong with yourself. Before entering into such a depressing state of mind, please read a few more lines. This average income path hides a lot of variation across different people. More importantly, it is strongly influenced by the very top earners. Figure 2 shows that the median worker only shows a 38% increase in his earnings between age 25 and 55. It is the very top earners who influence the 127% number before. For example, the Top 1% shows 1500% increase in their earnings in that same period. More than 300 times the median increase in earnings...
Figure 2: Earnings Growth (25 to 55) by Lifetime Earnings.
Another interesting finding is that income does not peak at the same age for everyone. Even though the average person's income peaks around the age of 50, this is not the case for most people. Figure 3 shows that the median worker has almost no income growth between 35 and 45, and only the top 2% actually experience earnings growth after 45.* I hope these depressing findings for the median worker might help your self-confidence. The average numbers shown in Figure 1 are not the appropriate ones to question your life. (Figures 2 and 3 might be...)
Figure 3: Earnings Growth by Decade of Life.
Some other interesting findings in these article are that the dispersion of income growth (i.e. how much income growth differs across individuals) has a U-shape, decreasing with age up to when people are 50 years old where it spikes up again. Top earners are the exception once again, since their income dispersion grows every year of their lives.
How about the asymmetries? Is it more likely to be below or above the average increase in income? The data suggests that as people get older or richer, it is more likely to get negative shocks to income. And these seems to be due to there being more room to fall down (not less room to move up). The higher your income, the more you can lose (remember most people are not willing to pay to work, so you cannot have negative wages).
Finally, let me end with a happy note. Suppose you just saw your income go down. You might be worried that it will remain like this for a long time. The data suggests otherwise. If the decrease was very strong, it is most likely that the persistence will be very short (unless you were a very high earner). In less than a year you should see your income recover most of its previous value.
(Very Small Print Note: this does not mean you should just lay down and wait for this fact to bring your salary back to normal. No complaints are accepted if incomes do not go up.)
* Remember that if a distribution is such that there are a few outliers with extremely high income growth, we will observe an average growth much higher than the one the median worker has. Hence, focusing on the median worker might be more illustrative in these cases.
Based on an article by Guvenen, Karahan, Ozkan and Song.
How much do children's social and economic opportunities depend on parents' income and social status? This is a politically correct way of asking: How doomed are children from poor parents?. The answer is essential to analyze policies that try to make every kids chances more equal. As always, a first step is to analyze what the data has to say about this. Fortunately, Chetty, Hendren, Kline and Saez (economists at Harvard and Berkley) are currently doing some beautiful analysis on this matter. Since opportunities are hard to measure, they focus primarily on income (although they also study education, crime or pregnancy) differences.
Using tax-income data on 40 million children born between 1980 and 1982 and their parents, they are going to rank people according to their income level. Parents are going to be ranked in groups from 1 to 100, according to how they do income-wise relative to other parents. Similarly, children are going to be ranked according to their incomes when they are 30-32 years old relative to the other children. Then, they are going to focus on two measures of intergenerational mobility:
1) Relative Mobility: What are the outcomes of children from low-income families relative to those from high-income ones?
Example: If my parents income increases by one ranking point, how much is my income rank expected to increase?
(The problem with this measure is that higher mobility may be due to richer people doing worse, not poor ones doing better. Hence, the second measure might be more useful.)
2) Absolute Mobility: What are the outcomes of children from families of a given income level in absolute terms?
For example, what is the mean income of a child born from parents in the 25th percentile?
The chart below shows the national statistics of the rank-rank (relative mobility) relationship in 3 countries: Canada, Denmark and US. The slope in the US is 0.341, while the other two are half that much. This suggests that increasing one percentage point in parent rank, increases child mean rank by 0.341 percentage points. The fact that Canadian and Danish data suggest higher relative mobility should be taken with caution since this could be due to worse outcomes from the rich, rather than better ones from the poor. Interestingly, this strong correlation with parents income rank is also observed in children's college (attendance and quality) and teenage pregnancy, suggesting differences emerge well beyond the labor market. This is consistent with evidence from my previous post.
The previous chart suggests that the rank-rank relationship is highly linear. Hence, the authors are going to take advantage of this when analyzing the intergenerational mobility across different areas in the US. The question now is: Is mobility the same across the US? Or are some regions better for children to make the jump forward? Given the issues with relative mobility, we can now focus on absolute mobility: What is the mean income of a child born from parents in the 25th percentile? The heat map below shows that the Southeast shows the lowest mobility in the country, while the Great Plains, West Coast and Northeast display much higher mobility levels (the map should be read the map as darker is worse mobility). While in some regions children of parents in the 25th percentile tend to remain in the same percentile when they grow up, in other areas similar children do twice as better (in income rank terms). This pattern seems robust to controlling for children moving to other areas and cost of living or demographic reasons like marriage differences.
The obvious next question is why are regions' mobility so different from each other? Why children in some areas seem to be born with more opportunities than those in other ones? This question is not directly addressed by the authors, but they provide some correlations with local characteristics. Given econometric issues like selection and endogeneity (also explained in a previous post!), the following should NOT be interpreted as causes.* However, they show interesting descriptive information.
1) Race and Segregation: The higher the share of African-Americans, the lower the mobility observed. However, the data suggests that this holds true for the white people in those areas as well. Hence, it is not that black people tend to remain stagnant. Segregation in the area seems to be correlated with everyone's mobility. Particularly, segregation of poverty seems to be the strongest reason (isolation of rich people does not seem to be behind). Some potential reasons could be: successful role models are not present for the poorest children; worse public goods provision; or access to jobs might be harder in such areas.
2) Income: The average income level is not correlated with mobility (i.e. it is not that richer areas do better or worse). However, areas with higher income inequality show lower degrees of mobility. Interestingly, the inequality in the upper tail is not correlated with mobility. Hence, it is not about the existence of some extremely rich people. It is more about the size of the middle class. The bigger the middle class, the higher the mobility.
3) School Quality: Better schools are associated with higher mobility.
4) Social Capital: Social participation in elections, census or even religious events is positively correlated with mobility.
5) Family Structure/Stability: The higher the number of single parents, the lower the mobility. Once again, this effect extends to children who are born from parents who remained together, suggesting that the effect is not at the individual level but at the social environment one. Regions with more divorce somehow have lower mobility.
To summarize, parents income seems to be very important on children opportunities. However, there is substantial variation across different areas in the US. Some areas seem to fit much better than others the concept of "Land of Opportunity." A child raised in the Great Plains has much better chances of making a leap forward than one born in the Southeast. Segregation, inequality and family structure are highly correlated with mobility. Unfortunately, why remains a mystery.
* Families choose where they live and what institutions they support. So we can imagine that families that prefer to live in areas with better education systems or less income inequality are intrinsically different than those that prefer to live in the more segregated South of the US.
How much is education worth? I personally believe that education provides you much more than just a higher income in the future, but let's simplify and focus here on how much more money you would earn if you studied a few more years. This question has interested economists for a long time (at least since Mincer in the 1950s). However, this holy number that could potentially explain whether I am (economically speaking) wasting my time doing a PhD has proved very hard to estimate. But let's start at the beginning.
Around the end of the 1950s, Mincer proposed - after building a rather simple model of human lives - doing a regression of (log) income to years of education and years of work experience. If you did this you would basically find that one year of schooling increased your income by between 10 and 14%. However, recent analysis by Heckman (and his army of co-authors) shows that returns to education are not that easy to estimate. Particularly, the effect of each year of education may not be the same across levels (e.g. the year you finish high-school is worth a lot more than any of the previous) and that education might change your future income growth due to years of experience (e.g. if you finish high school each year of work may bring you a higher increase in income than if you did not finish high school). This is seen in Table 3a below for white men both in 1940 and 1990 (bottom row is Heckman's and top row is Mincer's). Each column refers to a different year of education: 10-12 is finishing High School and 14-16 is completing college.
Another interesting finding here is that this would suggest that finishing high school in the 1990s is worth a lot more than it used to be in the 1940s (50% vs 24% income increase). Are we learning more nowadays? Possibly. But possibly not as well. This could come from a well known issue to applied economists: selection bias.
Let me introduce this concept with a (hopefully) clearer example that comes from the health sector: the number of deaths and hospitals. For every 100 people hospitalized for diagnosis in the US more than 2 die every year. On the other hand, for every 100 people in the US only 0.8 die every year.* Hence, comparing the two pools of people, anyone ill might think: "Wow! If I go to the hospital I increase my chances of dying by more than 100%. Then, I should stay away from hospitals and try to get better on my own." But this clearly makes no sense (at least not if you have health insurance!). You are comparing a pool of people who are sick (hospitalized) with a healthy one (everyone else). If the first one stayed out of the hospital, we would expect that more of them would die. And the same logic applies to education.
Focusing on the 10-12 column, these regressions are (intuitively) comparing people who finished high school with those who did not. But are these people equal in all other terms besides having finished school? Most likely not. We can imagine that people who don't finish high school have had a worse childhood, come from worse neighborhoods and are generally raised in a more distressed environment ("sick" in the hospital example above). This would suggest that even if this people did go to school they might do differently (worse?) in the labor market later on. Similarly we can imagine that the people who did finish high school had families with a better economic background who could more easily provide job opportunities to their children, hence increasing their labor income independently of schooling choices. Basically, the two groups of people cannot be compared directly. Hence, the increase in the observed returns could be because the pool of people who don't finish High School nowadays is (relatively) worse than the one in the 1940s. Most people finish high school nowadays, while this was not the case 60 years ago. In other words, the selection bias could have gotten worse over time.
What economists might like to do to solve the enigma of schooling returns is to randomly assign people to different education levels. Someone would be flipping coins and deciding everyone's education. This way we would be able to make sure that all kinds of people are equally distributed across the different education levels. And so the income levels of the different groups could be easily compared. Fortunately, economists are not allowed to dictate people's lives that much. And the best solution so far has been to look for uncontrolled events that make (some) people more likely to go to school (but are not related to their wages in the labor market directly). And then we compare this group to some other (similar) people who were not affected by such an event. A nice example comes from Seth Zimmerman and his estimation of returns to college admission.
Zimmerman focuses on a large public university in Florida (FIU), which was particularly easy to get in when compared to other universities (kind of like a last-resort university. Apologies to any FIU students reading this!). This way he can be more confident that if someone was not admitted there, they would not be admitted by another school. But, how does he separate people randomly into the two groups (admitted versus not admitted)? His trick is to take people just around the GPA admissions threshold. Figure 4 shows that people right above it are 23% more likely to be admitted to this university than students just below it (and more likely to attend as well).
Assuming that people are not able to control their GPA at this particular university, this would provide him with people being "randomly" assigned to "admitted" and "not-admitted" groups.** Hence, we can now compare the income across the two groups worrying less about selection. Figure 8 suggests that being admitted to college (i.e. from being just above the threshold) increases your income by around 22%.
It is important to notice a few limitations of this kind of studies. These econometric techniques don't come for free. This number is the return to college admission only for people who, for various reasons, are near the threshold. And once again, this people might be very different than the ones who had no trouble being admitted. So the 22% rate should be understood as the return to this particular group of people and not for everyone else. Nevertheless, this number might be the relevant one if you are thinking about a policy that changes the requirements for admission. Such a policy would affect this particular group and not the general population. Moreover, another drawback is that this return does not consider "General Equilibrium" effects: If such a policy were applied in all the country we would expect to have lot more people graduating in the next few years, which might affect the wages of college graduates. Hence, the returns to education might change.
Economics research can (sometimes) be extremely difficult when compared to physics and other such sciences. In these sciences nature's rule is well defined. It may be hard to understand but it is there, and all the data you observe is from such a rule. In economics, data observed is driven from people's different lives, crazy personalities, complicated families and interestingly different regions of the world. And on top of these differences (which we can't observe in the data), individuals are making choices which manipulate the data we economists try to work with. Hence, understanding humans and outcomes related to them can be very complicated. Like Stephen Hawking once said,
"While physics and mathematics may tell us how the universe began, they are not much use in predicting human behavior because there are far too many equations to solve. I'm no better than anyone else at understanding what makes people tick, particularly women."
* I would like to have the number of deaths of people not hospitalized to make the comparison with education but I wasn't able to find that number easily.
** Note that GPAs are computed differently by various universities. So students would need to preview that they want to apply to this particular school and be able to control their results very precisely to affect their result around the threshold. People way above the threshold can be easily thought to be very different, but people just above and just below the threshold are probably quite similar.
With the recent constant appearance of Alibaba on the news, the increasing relevance of Chinese exports to the world is extremely clear. Low-income countries accounted for just 9% of US manufacturing imports in 1990. But by 2007, they had more than tripled its share. And who do you think was behind this? China accounted for as much as 89% of this increase.
In this period, China's transition to an open economy included a massive 150 million people migrating from rural to urban areas. Imagine reallocating around half of the United States population geographically, with a particular focus on manufacturing production. Add to this formula novel access to foreign technologies as well as capital and Chinese exports growth to seem reasonable. However, did this come to the expense of anyone? This is the main objective of this post. One group being threatened by Chinese takeover of manufactures is obviously the manufacturing workers in the rest of the world. As these goods are easily tradable, we could expect job losses in these sectors. The figure below shows that as Chinese increased its relevance in US imports, the share of the population working in the manufacturing sector in the US decreased by one third.
However, many things could explain this decline. For example, it could be that Americans themselves were getting more educated and moving to other sectors. Alternatively, the service sector could be becoming more productive in the US, offering higher wages and hence draining employees from the manufacturing industries. These (and many other alternatives) do not involve China's exports growth. Moreover, they could be causing the increase in Chinese exports themselves. (Imagine US decides to get out of the production of manufactures, leaving a lot of unsatisfied demand which leads the Chinese to produce more). Hence, in order to make sure we are capturing the correct effect, modern econometric techniques come to the rescue! Autor and Dorn (AER, 2013) basically exploit the differences in the exposure to import competition across cities in the US. For example, it would be expected that - if the leading cause comes from the Chinese side - an area where manufacturing employed 25% of the people to be more affected by Chinese exports than an area that only employs 10% in manufacturing. Particularly, they will differentiate areas by how specialized they are in each division within manufacturing, and how imports from each of these changed over time. And these differences will give us the information we are after.
Looking at wages, the effect found of imports from China is negative. An increase in the imports per worker of around three thousand dollars (which was the average change from 1990 to 2007), would explain a decline of around 2.25% (0.76 times 3). More interestingly, this effect is stronger among men and people without college education. It is important to remark that this can only be calculated for the employed. Hence, if we expected workers with lower ability and earnings to be more likely to lose their jobs after the Chinese expansion, the effect on wages above would be understated. And so wages would have fallen even more for the whole sector, it's just that the effect could be hidden by the increasing number of people losing their jobs.
And what if we divide the effect between sectors? I would have expected the wage effect to be stronger in the manufacturing sector itself. But well, the data seems to suggest the opposite: wages seems to have been unaffected in this sector. However, the manufacturing sector was particularly affected by a major reduction in employment (predicting a decline of 12% due to China's increase in exports).
So most of the effect on wages mentioned for the whole economy seems to come from the non-manufacturing sectors. How can this be possible? Well, (adaptive) story telling is a prerequisite for any upstanding economist. And here is the one that seems most appropriate given the results: the increase in imports from China led to firing of the lower skilled workers in the manufacturing sector but had no effect on their average wages (note this could still involve a decrease in the wages of the ones that remained employed). Having no new paychecks, these newly unemployed decided to reduce spending and so decreased their purchases of services that have to be provided locally (like a haircut or a dentist). This reduced this local sector's revenue. Moreover, the newly unemployed also fled to other sectors looking for jobs. Having lower revenues and seeing lots of people of willing to work for less, other sectors reduced their wages.
Based on an article by David Autor and David Dorn (AER, 2013).
Most people (and particularly my mother) think that economics is only about money. That we economists are basically counting money and telling people where to invest. This post will be the first evidence that there is no boundary to economics. Today I will go as far as to fertility. Yes, we economists have a lot to say about fertility.
Fertility has interested economists for a long time. At least since Malthus' theory on population growth in 1798 economists have been interested in fertility. Malthus basically thought that as people became richer they would have more kids, which would mean less resources for everyone (he expected technological growth to be quite small), leading distress to knock on everyone's doors (though louder on the poorer doors). Fortunately, this is also an example of economists failure at predicting the future.
On top of human capacity to increase resources, which Malthus undervalued, the other assumption that does not hold in Malthus idea is that the higher your income, the more kids you have. But we will get to that later. Let's see the broad picture first. How has fertility evolved in the US in the last 200 years? Here is a plot of number of kids for (married) women born in different years (cohorts in the figure):
The dark blue line shows that the overall average of children born has decreased from a high 5.5. to an average of just below 2. More impressive is the fact that initial differences between groups (black vs. white, urban vs. rural) have narrowed substantially. Differences that used to be as high as 1.5 kids are now smaller than one-fifth of a child. Notice that this data is for married women, so hypothesis that are based on the reduction of marriage as a cause for the reduction in the number of kids are in trouble. It is also interesting to note that most of this compression is coming from the reduction of women having lots of children.
The number of women having either none or one kid has been quite stable around 10-20%, but the number of women having 4 or more children has diminished from almost 70% to below 10%. What seems to be behind this? There are many theories out there (see the paper cited below if interested), but I will stick here to the one of the most popular among economists: money, money, money...Here is a plot of number of kids for different levels of income for all the different cohorts.
The shocking thing about this picture is that all the women born from 1828 to 1958 seem to be gravitating around a constant relation between (real) income and number of kids had. In other words, in either century, women with incomes of around X apples (real income) would have in average a very similar number of kids. More impressively, there seems to be no difference in this relationship for either urban or rural areas. (Caveats aside) This suggests that the main difference between the average number of kids women have in the 1800s versus the 1900s (or in rural compared to urban areas) is mainly income. People are richer today and, for some reason, richer people tend to have less kids. The question is then why?
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