Tuesday, October 17, 2017

Migrating researchers are cited the most

This is according to a recent paper published in Nature. The authors analyzed 14 million papers published between 2008 and 2015 by nearly 16 million individual authors. Around 4% of those authors - more than 595K were considered to be “mobile,” meaning they had affiliations with academic institutions in more than one nation between 2008 and 2015. 

The study looks very interesting throughout. Here are only two of the main results:
  • "[...] mobile scholars have about 40% higher citation rates, on average, than non-mobile ones"
  • "Regardless of region, mobility pays in terms of citations. Across all regions, mobile scholars are more highly cited than their non-mobile counterparts. The advantage varies by region. Mobile North Americans see only a 10.8% boost in citations over their non-mobile colleagues. For Eastern European scholars, the gulf is 172.8%."
I thank Tim Schwanen for the pointer.

Monday, October 16, 2017

Two positions open at Oxford

Just a heads up to job seekers. There are currently two positions open at Oxford University. Perhaps some of you could be interested.

Tuesday, October 10, 2017

Insights from behavioural economics into transport planning and design

Yesterday, Richard Thaler was awarded the 2017 Prize in Economic Sciences "for his contributions to behavioural economics". In case you're interested on the topic, Erel Avineri has published a paper a few years ago where he discusses some of the insights that research in behavioural sciences can bring into the planning and design of transport systems to make them safer, sustainable and more efficient.

Avineri, E. (2012). On the use and potential of behavioural economics from the perspective of transport and climate change. Journal of Transport Geography, 24, 512-521.

Abstract:
It can be argued that the main thinking in transport planning and policy making stem from neoclassical economics in which individuals are largely assumed to make rational, consistent, and efficient choices, and apply cognitive processes of decision making that maximise their economic utility. Research in behavioural sciences indicates that individuals’ choices in a wide range of contexts deviate from the predictions of the rational man paradigm inspired the research agenda in the field of travel behaviour. New concepts and practices of government aim to apply some behavioural economics insights in the design of behavioural change initiatives and measures, an approach recently advocated in the US and the UK. This paper provides a brief review on the use and potential of behavioural economics from the perspective of transport and climate change, in two main contexts: travel demand modelling and design of behaviour change measures. The discussion of limitations and knowledge gaps associated with the implementation of behavioural economics to a travel behaviour context might contribute to the debate and help in defining research agenda in this area.

Why you should always visualize your data

In 1973, the statistician Francis Anscombe published a paper demonstrating the importance of plotting the data before analyzing it. That paper introduced what latter became known as the Anscombe's Quartet, which comprises four datasets that have almost identical descriptive statistics including means, variances and correlation and yet look completely different when you plot them.

This is how the Anscombe's Quartet look like.


This year, this idea has been taken to a whole new level. A couple of researchers took this idea very seriously and they developed a method to relocate the points in a scatterplot towards a given shape and still keep descriptive summaries seemingly identical. The authors published the method here. They've also developed an R library {datasauRus} so you can   procrastinate the whole afternoon  learn more about statistics.


Tuesday, October 3, 2017

The long-term effect of slavery on inequality today

According to a new working paper, 1800s slavery explains approximately 20% of income inequality in Brazil today. While the direction of the impact is not surprising, I'm impressed by its magnitude. I wonder how much investment in cash transfer programs would be necessary to achieve an effect of similar magnitude. Thanks John B. Holbein‏ for pointing to this study on Twitter.


Fujiwara, T., Laudares, H., & Caicedo, F. V. (2017). Tordesillas, Slavery and the Origins of Brazilian Inequality.

From the abstract:
"...To deal with the endogeneity of slavery placing, we use a spatial Regression Discontinuity framework, exploiting the colonial boundaries between the Portuguese and Spanish empires in current day Brazil. We find that the number of slaves in 1872 is discontinuously higher in the Portuguese side of the border, consistent with this power’s comparative advantage in this trade. We then show how this differential slave rate has led to higher income inequality of 0.103 points (Gini coefficient), approximately 20% of average income inequality in Brazil. To further investigate the role of slavery on economic development, we use the division of the Portuguese colony into Donatary Captancies. We find that a 1% increase in slavery in 1872 leads to an increase in inequality of 0.112. Aside from the general effect on inequality, we find that more slave intensive areas have higher income and educational racial imbalances and worse public institutions today"

ps. This paper also reminds me of this post on how presidential elections are impacted by a 100 million year old coastline in the USA. Hint: geology determined the distribution of productive land, which influenced the spatial distribution of African slaves which in turn influenced the electoral distribution. I'm not saying I'm convinced by this argument but I have to recognize it uses a quite inventive identification strategy.
image credit: Fujiwara et al (2017)

Sunday, October 1, 2017

Our biggest cities have existed and died before

Ta-Prohm, Cambodia, used to be the largest population settlement before the industrial revolution. Nowadays it is one of the most impressive ruins in the world.

"In reality, our biggest cities have existed and died before. This one did. It just happens over a longer period of time - the rain falls, the roots grow and nature eats what we built. The best technology of that time wasn't enough." Geat video by Joe Posner (Vox)


Friday, September 29, 2017

Urban Picture

Few cities are as photogenic as Barcelona from above #CatalanReferendum

Photo via City Describer

Wednesday, September 27, 2017

Uber ban in London

This week, it was on the news that Uber will soon lose its license to operate in London since the local transport regulator ruled that Uber is "not fit and proper" to operate in city. This decision is not settled yet and it's probably  hopefully  going to be negotiated along the appeal process towards a middle-ground regulation. 

In the meantime, Tyler Cowen's has shared his views on why this is "a big brexit mistake". This is part of a much larger debate on whether/how governments should regulate the 'sharing economy', a debate which would need a careful discussion on transport regulation. A paper on this very topic just got recently published and it does a really good job at tackling the most important points in this debate. The paper is coauthored by top researchers from the Transport Studies Unit TSU/Oxford   I'm biased . This is a very timely discussion in Brazil, where the Congress will be creating a national regulation  scheme for ride hailing apps in the coming months (link in Portuguese).


Dudley, G., Banister, D., & Schwanen, T. (2017). The Rise of Uber and Regulating the Disruptive Innovator. The Political Quarterly.

Abstract
The ride-hailing company Uber has achieved extremely rapid global expansion by means of outmanoeuvring governments, regulators and competitors. The rise of the company has been based on a deliberate strategy of acting as a market disruptive innovator through a user friendly technology and making use of the ‘sharing economy’. These attributes are not unique, but are distinctively augmented by a relentless expansionary ambition and an ability to maintain the capacity to innovate. Uber has generated great political controversy, but the challenge for governments and regulators is to embrace the benefits of the disruptive innovator, while adopting an approach that takes into account the full range of impacts. For Uber, the challenge is to maintain its expansionary style as a disruptive innovator, while also redefining on its terms the political and public debate. The case study of London provides important insights into the dynamics of these processes.

image credit: DANIEL LEAL-OLIVAS/AFP/Getty Images

Monday, September 25, 2017

Assorted Links

  1. The next time you have "a new idea no one's thought of before", read this list, be humble and go back to  Google  the library.

  2. This website helps you select a projection for your map (paper here)

  3. Mapping London’s “pseudo-public spaces,” spaces “that appear to be public but are... controlled by developers.” via Geoff Manaugh

  4. How One Brilliant Woman Mapped the Ocean Floor’s Secrets via Sabrina Lai, who is the creator/admin of a great group about Geographical analysis, urban modeling, spatial statistics on Facebook

  5. Infographic of the fascinating timeline of the far future via Tyler Cowen
    1. In a 100 million years from now: “Future archaeologists should be able to identify an ‘Urban Stratum’ of fossilized great coastal cities, mostly through the remains of underground infrastructure such as building foundations and utility tunnels.”.

  6. 100 greatest images of Saturn from its Cassini Mission

  7. Heads up for some great opportunities:
    1. University of California, Santa Barbara Department of Geography invites applications for a tenure-track position in spatial data science
    2. The Ohio State University, Department of Geography invites applications for a tenure track position with expertise in areas such as spatial-temporal data analytics, spatial simulation and modeling, cyberGIS and high performance computing, and/or geovisualization
    3. University of Texas St Antonio is hiring a tenure track/Associate demographer who works with big data

  8. Beautiful data visualization of music, by Nicholas Rougeux

    This is a data visualization of Vivaldi’s Four Seasons. You should read it read clockwise.
    Size = note length
    Distance from center = pitch
    Colors = instruments.

Wednesday, September 20, 2017

Public transport and school location impacts on educational inequalities in Sao Paulo

In 2016, I had the opportunity to attend a session at the AAG conference where Ana Moreno-Monroy presented a very interesting paper analyzing inequalities in school accessibility by public transport  in Sao Paulo. The paper is coming out in the Journal of Transport Geography and it's coauthored by Robin Lovelace and Fred Ramos, such a great team. I should also note that a big chunk of the data analysis was conducted in R using stplanr, a library for transport planning developed by Robin and Richard Ellison and which is a major contribution to the field.


Moreno-Monroy, A. I., Lovelace, R., & Ramos, F. R. (2017). Public transport and school location impacts on educational inequalities: Insights from São Paulo. Journal of Transport Geography.

Abstract:
In many large Latin American urban areas such as the São Paulo Metropolitan Region (SPMR), growing social and economic inequalities are embedded through high spatial inequality in the provision of state schools and affordable public transport to these schools. This paper sheds light on the transport-education inequality nexus with reference to school accessibility by public transport in the SPMR. To assess school accessibility, we develop an accessibility index which combines information on the spatial distribution of adolescents, the location of existing schools, and the public transport provision serving the school catchment area into a single measure. The index is used to measure school accessibility locally across 633 areas within the SPMR. We use the index to simulate the impact of a policy aiming at increasing the centralisation of public secondary education provision, and find that it negatively affects public transport accessibility for students with the lowest levels of accessibility. These results illustrate how existing inequalities can be amplified by variable accessibility to schools across income groups and geographical space. The research suggests that educational inequality impacts of school agglomeration policies should be considered before centralisation takes place.


Figure 2. Visual representation of the 12,697 OD pairs routed through the Google Distance Matrix API on an interactive map in RStudio, an open source data analysis platform.


credit: Moreno-Monroy et al 2017

Sunday, September 10, 2017

Biographical note: moving to Brasilia

In the next couple of days, my partner and I are moving back to  the lovely but car-dependent  Brasilia, in Brazil . We had a wonderful time in the UK after three years in Oxford and one year in Cambridge. I don't have the words to say how much I appreciate the privilege it was to live among such vibrant and global academic communities and how eye-opening this whole experience has been. Time has flown by and I am now returning to my researcher position at the Institute for Applied Economic Research (Ipea).

It feels bittersweet going back to Brazil for various reasons. Perhaps the most important of them is the fact that I haven't finished my PhD yet. I am close to the end, though, and I will soon post some updates about my research.

I also must say it is impossible not to feel disappointed with the economic and political situation in Brazil these days. Nonetheless, I am glad to go back to home, where evidence-based policy is so much needed and where I will keep expanding my (inter)national collaborations. I'm particularly glad that I am going back to a great institution where I can use what I've been learning during my PhD to do policy relevant research. Looking forward to next chapters  I need to finish my PhD first .

Home again

credit: the talented Joana França


Soundtrack:

Saturday, September 9, 2017

Urban Picture

Stunning construction photos of Zaha Hadid's Leeza SOHO tower, in Beijing. Photo by Satoshi Ohashi. Thanks Jeroen Apers for the pointer

Photo: Satoshi Ohashi

Wednesday, September 6, 2017

The paradox of collective choice

In the early 1950s, Kenneth Arrow published his PhD thesis where he demonstrated that it does not exist a method of converting individual preferences into a single group preference that is not limited by a 'voting paradox' at some point. Here is a great video explaining in layman's terms how Arrow's impossibility theorem works.

Needless to say how important this idea is for social choice theory and that it gave Arrow a Nobel Prize in economics. Curious fact. Five of Arrow's former students have won the Nobel Prize.


Monday, August 28, 2017

Transport access to health services

As some of you might remember from an earlier post, my PhD research concentrates on questions of transportation equity, particularly focusing on issues of transport accessibility and inequality of opportunities. Because there is a substantial overlap between my PhD and the research on spatial access to health services, I've read quite a few papers in this literature.

This is a well-studied topic with plenty of publications for those interested.  if you would ask my opinion  I would strongly recommend these two papers below. Together they give a good summary of the cutting-edge research and a very thorough review of various approaches to measuring transport access to health services.



Types of distance. (a) Cartesian distances. (b) Network distances

credit: Apparicio et al 2017

Thursday, August 24, 2017

3D reconstruction of the Brasilia madness

A beautiful 3D reconstruction of the Brasilia madness. It is a shame the video forgot about the men and women who built the city, but it's still a beautiful tribute to the work of Oscar Niemeyer and Lucio Costa.

Saturday, August 19, 2017

Magic roundabouts

Behold the "magic roundabout" in Swindon, England. It is a roundabout formed by 5 smaller roundabouts arranged around a sixth central, anticlock wise roundabout. I would also called it 'magic' if I managed to drive through it and survive. Jokes aside, it seems pretty safe.

Apparently, this is a thing in the UK where they have four other magic roundabouts. Here is how the one in Swindon works:

Friday, August 18, 2017

Social class and commuting in London from 1800 to 1940

In this video Simon Abernethy talks about his PhD thesis where he looked at how public transport shaped the distribution of social classes in London from 1800 to 1940. The interview covers some interesting details about the daily life of suburban commuters back then. I think some urban historians might enjoy it. Looking at you Yuri Gama.

This is a relatively old interview, though. It was recorded in 2013 and Simon has published a few studies since then.


Saturday, August 12, 2017

An R library to analyze and map John Snow's 1854 Cholera data

As many of you will know, an English physician called John Snow mapped the cholera outbreak in the Soho district of London in 1854. That map would later be a key element in the discovery that cholera was caused by contaminated water, not air. It's fair to say this map somehow changed history not only because of the lives it helped save, but perhaps more importantly because of the ways it opened human imagination to the role of spatial analysis in science and human development. Steven Johnson has written a book about the story of this map and its influence on modern science and cities. If you are short in time, there is a great 9-minute video summary of the book here.

All this introduction to say that now there is an R library that allows you to analyze and map John Snow's 1854 Cholera data yourself. Thanks Bob Rudis for calling attention to this library on twitter. Dani Arribas-Bel also pointed out to this chapter / online notebook that presents the documented code for a reproducible spatial analysis of John Snow’s map using mostly Python. This is great material for teaching.

update 16 Aug 2017: RJ Andrews has also pointed me to this paper analyzing the mortality rates and the space-time patterns of John Snow’s cholera epidemic map.



Sunday, August 6, 2017

Saturday, July 29, 2017

Computational social science and the dynamics of social trust

Just a quick  procrastination  post today since I'm still working on the paper I'll submit to TRB.

I read a few days ago a great piece by Pseudoerasmus (Twitter) on 'Where Do Pro-Social Institutions Come From?'. It's a long read but it gives a nice and beautifully written overview on the recent research on the dynamics of social trust and its relation to collective action, culture, institutions and evolutionary game theory.

On a related topic, I just saw today the new project by Nicky Case. Nick is a star programmer/interactive designer that uses code to build interactive websites to explain scientific theories to the wider public. He has many interesting projects so be aware you might loose a day or two playing with his projects. In his latest project, Nick applies computational social science to game theory to explore the dynamics of social trust. It's a super well designed project that explains in simple terms such a complex topic. I think this is a great complimentary material to Pseudoerasmus' piece and in fact to any course on collective action, social trust, game theory, chaos and complexity theory.

Now go on. Take 7 minutes of your day and give it a try. It's worth it. If you don't have 7 minutes, this is the main take away.
"If there's one big takeaway from all of game theory, it's this: What the game is, defines what the players do. Our problem today isn't just that people are losing trust, it's that our environment acts against the evolution of trust. [...] In the short run, the game defines the players. But in the long run, it's us players who define the game"

Friday, July 21, 2017

The high cost of free parking

Nice video by Vox and the Mobility Lab team on how parking requirements shaped American cities. Via Jeff Wood



Thursday, July 20, 2017

Map of the day: the public transport network of Tokyo

Simon Kuestenmacher tweeted the other day this map that shows the public transport network of Tokyo metropolitan area (higher quality image in Japanese here). Tokyo is today the largest metro area with almost 38 million people. The amount of planning and daily work they put in their transport network overt the decades it just jaw dropping, as this maps can tell. 

Monday, July 17, 2017

Vertical Hong Kong

Beautiful drone footage of Hong Kong, by Mariana Bisti (2017). It's better in full screen.




Friday, July 14, 2017

Heads up for some useful R packages

As you can see from this post, the community of R users and developers is alive and kicking on Twitter. If you would like to recommend other packages, send me an email or leave a comment on this post.

  1. data.table: high-performance data manipulation, by Matt Dowle and Arun Srinivasan. This is certainly among my favourite packages. I've been working with datasets of a few hundreds of millions observations and it makes things much faster. I stopped using dplyr long time ago


  2. tidycensus: a new library to get the US Census Bureau spatial and demographic data in R ready for use with sf and the tidyverse. This package was created by Kyle Walker, who is a must-follow if you're into R and spatial analysis


  3. mapview: interactive viewing of spatial objects in R, by Tim Salabim


  4. mapedit: interactive editing of spatial data in R, by Kent Russel






  5. ggsci, a collection color palettes inspired by colors used in scientific journals to be used in ggplot2, by Nan Xiao


  6. ourworldindata: a package by Simon Jackson to access the datasets from OurWorldInData.org, which is a great project by Max Roser


  7. magick: advanced image-processing in R, which can be really useful for including gifs in your plots and impress reviewer #2 . ht Danielp Hadley


Sunday, July 9, 2017

Thursday, July 6, 2017

Bicycles empower women: evidence from a quasi-experiment in India

In 1896, the American civil rights leader Susan B Anthony wrote about the crucial role that the bicycle had in women's emancipation and independence. Gradually, more and more evidence shows she was right.

Four years ago we posted about a study by K. Muralidharan and N. Prakash, who analyzed an Indian program "... aimed to reduce the gender gap in secondary school enrolment by providing girls who continued to secondary school with a bicycle that would improve access to school". They have found that the program was an extremely cost-effective way to increase girls’ access to secondary schools and enrolment rates. Their paper just came out published in the American Economic Journal: Applied Economics. (ungated older version here).

Muralidharan, K., and Prakash, N.. 2017. "Cycling to School: Increasing Secondary School Enrollment for Girls in India." American Economic Journal: Applied Economics, 9(3): 321-50. 

Abstract
We study the impact of an innovative program in the Indian state of Bihar that aimed to reduce the gender gap in secondary school enrollment by providing girls who continued to secondary school with a bicycle that would improve access to school. Using data from a large representative household survey, we employ a triple difference approach (using boys and the neighboring state of Jharkhand as comparison groups) and find that being in a cohort that was exposed to the Cycle program increased girls' age-appropriate enrollment in secondary school by 32 percent and reduced the corresponding gender gap by 40 percent. We also find an 18 percent increase in the number of girls who appear for the high-stakes secondary school certificate exam, and a 12 percent increase in the number of girls who pass it. Parametric and non-parametric decompositions of the triple- difference estimate as a function of distance to the nearest secondary school show that the increases in enrollment mostly took place in villages that were further away from a secondary school [> 3km], suggesting that the mechanism of impact was the reduction in the time and safety cost of school attendance made possible by the bicycle. We also find that the Cycle program was much more cost effective at increasing girls' secondary school enrollment than comparable conditional cash transfer programs in South Asia.


And here is an old video briefing on the study.

Assorted Links
















  1. Using geographic profiling to investigate the real identity of Banksy. There is a nice interview with one of the authors about the paper in the podcast 'What's the point'

Monday, July 3, 2017

The rise of 'nuance' in the Social Sciences

About two years ago, we put a link to Kieran Healy's work titled "Fuck nuance". His study has now been published as a paper in Sociological Theory (ungated version here). One of his main arguments is that the search for more nuanced understandings of social phenomena often end up obstructing the development of robust social theories. This is certainly open for debate.

Although Kieran's paper focuses on studies in Sociology, he has recently expanded some his analysis to other fields of the social sciences, showing how the the percentage of articles mentioning the words ‘nuance’ or ‘nuanced’ has sharply risen since the 1990s in pretty much every field.



credit: Kieran Healy

Thursday, June 29, 2017

World population distribution by altitude

Another interesting chart by Bill Rankin, this one showing how the world population is distributed by altitude.
  • 6% of the world's population leaves above 1.6 Kilometres (1 mile)
  • 50% leaves below 165 meters of altitude
  • 0.2%  leaves below sea level
click on the image to enlarge it

Sunday, June 25, 2017

7th Anniversary of Urban Demographics !

Today is the 7th Anniversary of Urban Demographics. I hope the blog has been a valuable source of  procrastination  information for you as much as it has been for me. Thanks all the readers for the support \o/

Here are some stats that show a summary of the blog over the past year. Please, feel free to drop me a line with suggestions on how to improve the blog. If you have any criticisms, please direct them to this other blog here.


The most popular posts:
  1. How Brazil compares to other countries in terms of area, population and human development
  2. Mexicans didn’t cross the US border. The border crossed them 
  3. The people who keep us company throughout our life cycle
  4. Comparing house price trends worldwide
  5. The world’s most violent cities

and 10 of my favourite posts:
  1. How much of the world is covered by cities? not much
  2. The impressive expansion of subway systems in China
  3. Distributive justice and equity in transportation
  4. The cost of every Olympics Games since 1960
  5. Creating an animated world map of life expectancy changes from 1950 to 2100 in R
  6. Mapped history of population expansion in the US
  7. Income segregation at the block level
  8. Measuring exposure to air pollution using mobile phone data
  9. Map of Population Density Lines in R
  10. Visualizing the space-time geography of flow data

Where do readers come from? (202 Countries - 4,482 Cities) 
  • Brazil (44.6%) 
  • United States (17.9%) 
  • United Kingdom (4.6%) 
  • Mexico (2.8%) 
  • Russia (2.7%) 
  • other countries (27.4%) Not many readers in Siberia nor Greenland, though


    Thursday, June 22, 2017

    Urban Picture: Venice from above

    This picture comes from the Earth View, an extension for Chrome that displays some really beautiful satellite images from Google Earth every time you open a new tab. 

    ps. and some people tell me I procrastinate too much, yeah right.


    Wednesday, June 21, 2017

    Difference-in-differences for spatial data

    It just came to my knowledge today that Raymond Florax passed away a couple of months ago (in memorian). Prof. Florax was very influential in the field of spatial econometrics. In one his latest papers, he co-authored with Delgado and proposed a difference-in-differences method for spatial data, controlling for spatial dependence. Here is the paper.

    Delgado, M. S., & Florax, R. J. (2015). Difference-in-differences techniques for spatial data: Local autocorrelation and spatial interaction. Economics Letters, 137, 123-126.


    Abstract:
    We consider treatment effect estimation via a difference-in-difference approach for spatial data with local spatial interaction such that the potential outcome of observed units depends on their own treatment as well as on the treatment status of proximate neighbors. We show that under standard assumptions (common trend and ignorability) a straightforward spatially explicit version of the benchmark difference-in-differences regression is capable of identifying both direct and indirect treatment effects. We demonstrate the finite sample performance of our spatial estimator via Monte Carlo simulations.

    Tuesday, June 20, 2017

    Assorted links

    1. Personal details of ~200 million US citizens exposed. A 1.1 terabyte data set with names, home addresses, phone numbers, political views etc. This is approx. 2/3 of the american population. Probably the largest data leak in history  thus far 






    2. I've recently found out that the principal scientist at Amazon‘s Modeling and Optimization team is Renato Werneck, a Brazilian researcher who is also one of the authors of Raptor, the Round-Based Public Transit Routing algorithm






    3. In the USA, both Democrats and Republicans agree there is a lot of discrimination against certain social groups. They just disagree which groups are discriminated against


    4. Health Effects of Overweight and Obesity in 195 Countries over 25 Years. Since 1980, obesity rates doubled in more than 70 countries and continuously increased in other countries

    Prevalence of Obesity at the Global Level, According to Sociodemographic Index (SDI)

    [click on the image to enlarge it]


    Sunday, June 18, 2017

    The effect of Uber on traffic congestion

    Early this year, a paper in PNAS using a computer model estimated that car sharing services like Uber and Lyft could reduce the number of taxi vehicles on roads by ~76% without significantly impacting travel time. As Joe Cortright has said, the authors are overly optimistic. 

    There is another study from last year that analyzed what actually happened to congestion levels when Uber entered the market in some US cities (abstract below). The results of this study are not really comparable to the the paper in PNAS, though. The methods are sound but I have the impression the authors pay too much attention to the statistical significance of the results and do not really discuss the magnitude of the effects of Uber entry on congestion. In any case, it's a good read. 


    Li, Z., Hong, Y., & Zhang, Z. (2016). Do Ride-Sharing Services Affect Traffic Congestion? An Empirical Study of Uber Entry. Available at SSRN: https://ssrn.com/abstract=2838043

    Abstract:
    Sharing economy platform, which leverages information technology (IT) to re-distribute unused or underutilized assets to people who are willing to pay for the services, has received tremendous attention in the last few years. Its creative business models have disrupted many traditional industries (e.g., transportation, hotel) by fundamentally changing the mechanism to match demand with supply in real time. In this research, we investigate how Uber, a peer-to-peer mobile ride-sharing platform, affects traffic congestion and environment (carbon emissions) in the urban areas of the United States. Leveraging a unique data set combining data from Uber and the Urban Mobility Report, we examine whether the entry of Uber car services affects traffic congestion using a difference-in-difference framework. Our findings provide empirical evidence that ride-sharing services such as Uber significantly decrease the traffic congestion after entering an urban area. We perform further analysis including the use of instrumental variables, alternative measures, a relative time model using more granular data to assess the robustness of the results. A few plausible underlining mechanisms are discussed to help explain our findings.

    A good-looking video of the computer simulation model of the PNAS paper.


    Thursday, June 15, 2017

    Mexicans didn’t cross the US border. The border crossed them


    Carlos Goes pointed me to this short piece in The Economist:
    "... communities have proved more durable than borders. The counties with the highest concentration of Mexicans (as defined by ethnicity, rather than citizenship) overlap closely with the area that belonged to Mexico before the great gringo land-grab of 1848."
    For the most part, Mexicans didn’t cross the US border. The border crossed them.


    Wednesday, June 14, 2017

    Getting updates from Urban Demographics blog

    This week we have crossed the milestone of 5000 followers on Twitter. If anything, this means there are a lot of procrastinators out there. If you're not on Twitter but you would like to  procrastinate  receive automatic updates when there is a new blog post, there are two options:

    (1) You can subscribe to our RSS Feed in a reader . I'd recommend using Feedly. (2) Or you can get updates from our Facebook page.




    if you like this blog, recommend it to your friends. If you don't like this blog, recommend it to your enemies. That's also fine.

    Monday, June 12, 2017

    The people who keep us company throughout our life cycle

    Henrik Lindberg has put together this nice chart showing the people we spend the most time with throughout out life cycle. The data comes from the America Time Use Survey, and the the code to create this chart in R is available here. Thanks Steve Williams for the pointer.

    This might be a good moment to reflect about life.

    Friday, June 9, 2017

    Time-lapse: Nightfall over Los Angeles

    Nightfall, by Colin Rich. Remember to watch in high-definition full screen. Via Aaron Renn from Urbanphile.


    NightFall from Colin Rich on Vimeo.

    Wednesday, June 7, 2017

    The Fundamental Law of Road Congestion

    Duranton, G., & Turner, M. A. (2011). The fundamental law of road congestion: Evidence from US cities. The American Economic Review, 101(6), 2616-2652. Ungated version here.

    Abstract:
    We investigate the effect of lane kilometers of roads on vehicle-kilometers traveled (VKT) in US cities. VKT increases proportionately to roadway lane kilometers for interstate highways and probably slightly less rapidly for other types of roads. The sources for this extra VKT are increases in driving by current residents, increases in commercial traffic, and migration. Increasing lane kilometers for one type of road diverts little traffic from other types of road. We find no evidence that the provision of public transportation affects VKT. We conclude that increased provision of roads or public transit is unlikely to relieve congestion

    This paper reminds of the Black Hole Theory of Highway Investment, which we posted about a while ago.