Tuesday, August 21, 2007

Some more data visualizations - UK house prices

Since looking (and screaming) at the Greatest Ever Data Visualization, I was curious to see what UK house prices have looked like over time (spurred on by my sister who lives there, and was curious to see what it would look like):

House Price by Year

This is a pretty nasty looking trend.

A couple of points though. The vertical scale is plotted against the average of the distribution, not the actual house price. This is because I couldn't (easily) figure out how to adjust the scale in Swivel (something I will be trying to find out how to do later). However, the trend when plotting against the average and the actual values trend is about the same - all equally as scary!

The house prices are for the UK as a whole and came from Nationwide's very useful data download facility.

The adjusted figures were from entering the unadjusted house price into this calculator. It uses the Retail Price Index (RPI) to calculate the value of the price in 2006 pounds. This seemed to be a logical thing to do - adjusting for inflation in everyday goods (as that is how you tend to 'value' your money). However, I have seen shorter runs of adjusted house price data that have different price levels, if similar trends. If anyone knows what additional adjustments are used, please let me know. I might have a bit of a poke around some economic sites to try and find out.

Next step, plotting it to a roller coaster.... stay tuned.

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Anonymous said...

this is all very interesting but why dont you plot something like the relationship between player investment in premiership football teams and their total points at the end of the season?

London said...

You have used Nationwides data. What is interesting is if you use maybe rigthmoves or the RICS data, you will get a different result. Thats the problem with having all these standards to calculate the same thing: house prices!

It would be interesting to see a graph for specfic cities, maybe like London.

Paul Soldera said...

Anonymous - I'd love to get my hands on some data regarding Premiership investment - that would be interesting. I'd expect some sort of relationship, maybe with a time lag component - investment by points over three seasons or something.

London - I originally wanted to do this for London, but couldn't find a historical data set that went back far enough. I have some other regional data I might put up, it's interesting as well. Maybe a inner London, Manhattan comparison.

I'd also be surprised if the long term trend differed significantly by data source - they all seem to be calculated in relatively similar ways. But again, it was finding the historical data that was hard - Nationwide was just the best source. I originally wanted to go back to the 1800s!

Isabel said...

Check out Robert Shiller's housing price index for the United States; the graph shows that inflation-adjusted housing prices in the U. S. were between 75% and 125% of their "historic" (1890) values for a long time, but currently are about double what they were historically. Some people seem to doubt that prices remain roughly constant after inflation, but even so something crazy is going on these days.