“Calling Abidjan” – estimating population distribution through analysis of mobile phone call data records

Big data, big challenge? Together with Harald Sterly of the University of Cologne I presented a little piece of research in the Extended Spatial Analytics session of the German Geography Congress (Deutscher Kongress für Geographie) in Berlin. The project “Calling Abidjan” that we worked on with Kouassi Dongo of Université de Cocody-Abidjan was started after we successfully applied for participation of the D4D Challenge. According to the initiator Orange telecommunications ‘Data for Development’ is “an innovation challenge open on ICT Big Data for the purposes of societal development”. The project allowed us to work with anonymised mobile phone data from individual call records by Orange in the country of Côte d’Ivoire (Ivory Coast).
We were interested in investigating, what non-computer scientists with a social science and urban planning background can do with such data in a more contextual rather that technically driven way and therefore explored how mobile phone call records can be used to better estimate population distribution.
For our analysis we used anonymised call data records consisting of information about the base station, timestamp, and caller ID produced by the approximately 500.000 Orange Télecom users in the country. There were 1079 base stations at the time the data was generated and we were able to work with data covering 183 days. The dataset consisted of 13GB of raw data which some would perhaps call ‘Big Data’ (though I personally do not like this term for many reasons).
The following two (draft) maps give an insight into the results. The purple circles show the distribution and density of population estimates that we derived using only mobile phone call records dataset. To better see the correlation with what other population data tells us about where people live, we did not only produce a normal land area map (on the left, also displaying some basic idea of the topography in the country) but also showed the data on a gridded population cartogram which we generated from the LandScan population grid, the perhaps most detailed population dataset currently available on a globally consistent high-resolution basis:

Population maps of Ivory Coast / Côte d'Ivoire created using Mobile Phone Call Records
(click for larger version)

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Visualising your UK constituency

The UK general election is fast approaching. Following the first almost-debate of the would-like-to-be Prime Ministers the battle for the ‘correct’ interpretation of the state of the nation has come into its final stage. Statistics are easy to twist, and there is never an absolute truth in them. In a collaboration with the Office for National Statistics I was involved in the creation of a little interactive visualisation feature that sheds light on some key statistics that show life in the constituencies around the country. Using a conventional map and a hexagon cartogram of the United Kingdom we looked at house prices, income, public sector employment, education, age, migration, and health which can be interactively explored and compared in both map views. The following map is one example from that feature, showing the share of people not born in the United Kingdom:

Cartogram and map showing the share of the population born abroad in the United Kingdom
(click for larger version)

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Geographic visualization in social sciences: Draw more maps!


Wordle Data Visualisation
Geographic visualization in social sciences – or draw more maps! Continue reading

Visualization of Satellite Data Availability

The currency of geodata is an important factor for many advanced geospatial applications. Examples for this are security questions in the control of international borders and coastal areas, or up-to-date information following natural hazards. Here a near real time availability of geoinformation is of high value. A wide range of commercial satellites providing near real time information are available. Satellites with active sensors, such as Synthetic Aperture Radar (SAR) systems, can deliver such information even at night and in areas with cloud coverage.

Cartogram visualisation of the TerraSAR-X and TanDEM-X latency
(click for larger version)

The German SAR satellite mission with the TerraSAR-X and TanDEM-X satellites provides coverage of every location on earth within 1-3 days. The acquired data can be made available for processing within hours or in certain cases even minutes. Continue reading

In Focus: The real size of Offshore Financial Centres


Political InsightIn an article for the “In Focus” section of Political Insight (December 2013, Volume 4, Issue 3) Jan Fichtner of the University of Frankfurt a.M. and I analysed the size of the foreign assets in the world’s largest offshore financial centres. All ‘offshore financial centres’ (OFCs) have one characteristic feature in common; they offer very low tax rates and lax regulations to non-residents with the aim to attract foreign financial assets. OFCs essentially undercut ‘onshore’ jurisdictions at their expense. The main beneficiaries are high-net-worth individuals and large multinational corporations that have the capital and expertise required to utilise OFCs. Beyond its geographical connotation the phenomenon of ‘offshore’ represents a withdrawal of public regulation and control, primarily over finance. Some important OFCs are in fact located ‘onshore’, e.g. Delaware in the USA and the City of London in the UK. However, historically many OFCs have literally developed ‘off-shore’, mostly on small islands.
OFCs as defined by Zoromé (2007) are jurisdictions that provide financial services to non-residents on a scale that is excessive compared to the size and the financing of their domestic economies. The graphic shows combined data on securities (Coordinated Portfolio Investment Survey by the IMF) and on deposits/loans (Locational Banking Statistics by the BIS) at the end of 2011. Capturing the two by far most important components of financial centres allows a reasonable approximation of the real size of OFCs while avoiding double counting. The larger the size of the circles on the map, the more foreign financial assets have been attracted to the particular jurisdiction. The vast majority of the almost US$70 trillion foreign financial assets are concentrated in North America, Europe and Japan. Areas with assets below $US50bn are not shown for their relative insignificance in the global context.

Offshore Financial Centres

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Where the Wild Spaces Are: Un planeta salvaje

Make the world a wilder place | Por un planeta más salvaje
Where the Wild Spaces Are - WILD10 Conference 2013, Salamanca, Spain

Wilderness and remote areas are a diverse element in the patchwork of spaces that form the land surface of our planet. Only very small amounts of people are living in sparsely populated areas, which is an expression of the strong organisation of human societies to maximise those living in close relative proximity. More than half of the world’s population now lives in areas categorised as cities, and although more than 95% of the world’s population live in approximately only 10% of the land area, the remaining 90% of space on land are far from being uniform remote or even wild areas.
There are very different ways of how the un-built area that still makes the largest share of land can be understood in terms of being under influence and in reach of human civilization. Only 15% of people in rich countries live more than an hour of travel time from a city (of at least 50,000 people), while the same applies to 65% of people living in the poor countries of the world. This paper demonstrates a different approach to visualising and understanding these loneliest places on the planet by using a technique called a gridded cartogram transformation. The following map shows a gridded cartogram visualising the relative distance of areas to the majority of people. The maps derived from the distorted grid show the physical space transformed according to the absolute travel time that is needed to reach the nearest major city by land transport averaged over the area of a grid cell, resulting in a map that gives the remotest places most space and provides a unique new perspective on the spatial dimension of remoteness:

(click for larger version – high resolution PDF)

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