Project description

The Economist has been gathering and publishing national-level house-price statistics since the early 2000s. Before the US sub-prime mortgage crisis began in 2007 The Economist correctly warned of the dangers of an over-heating US housing market and the risks to the wider global economy. It is only since the financial crisis that economists have realised the importance of good and timely house-price data in an effort to spot asset bubbles before they burst.

Our interactive chart of house prices allows users to explore the gyrations in national housing markets for 27 economies—and for 25 American cities—from 1970 to the present date. We offer up four metrics of housing data: nominal and real (inflation-adjusted prices) and two valuation metrics, comparing prices against income and against housing rents.

We expect our interactive to have wide appeal: from individuals wondering how affordability or house-price inflation in their country compares against others, to macroeconomists seeking good data on global housing-market trends.

What makes this project innovative?

Our house-price index is unique in that it gathers official data from multiple sources and across different spatial levels. It also provides useful valuation metrics, and visualises the data all in one place. To our knowledge, there is no other tool that does all of this. We wanted to build a responsive, modern interactive graphic, as most governments and other agencies only publish static images and long reports on the topic.

The ability to compare housing within different countries and cities allows users to build their own understanding, while comparing, for example, the effect of the housing bubble before and after the financial crisis. Housing is a very hot topic, and having high-quality data in an explorable form is valuable for the public debate.

What was the impact of your project? How did you measure it?

The interactive was referenced by industry professionals, and thousands of users explored the data through the tool. Many also created and shared screenshots showing their findings. The article on had a read-time of over 750 hours and we are hoping for repeat visits when we update the underlying data.

Source and methodology

The data are compiled from a number of sources: OECD; national statistical agencies; and some private companies (Zillow for US cities; Vdp Research for Germany). The Economist has been gathering and presenting house-price data since the early 2000s, but there have been a number of innovations since then. We first included valuation metrics in 2009; and have expanded the number of countries we cover. US cities were first published in 2012.

The data are gathered and cleaned using R scripts which helps to automate much of the fiddly work. This also reduces the chances of introducing errors.

Technologies Used

The Economist has used interactive charts to visualise its house-price data since 2007. Our old interactive was functional, but it looked tired and was not responsive. We wanted to make something more ambitious and modern, with quick feedback and more data. To build the new interactive we used a combination of React, D3 and our in-house charting library. This combination was useful for coordinating the different views of the graphic and the dozens of options that we decided to add later on.

Our library is heavily inspired by ggplot, and works by adding different geometries to a frame. That approach favours a fast iteration cycle while keeping all our styles consistent.

Project members

James Fransham
Martín González


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