How much data do you need?

I’ve been playing about with data pertaining to Herefordshire as part of a project for The Bulmer Foundation.

There is a lot of data out there. At a rough guess hundreds of datasets of public data that pertain to Herefordshire. And I’m just imagining data that you could put into a nice simple table. When you factor in mapping data and unstructured data the levels become very large indeed. And Herefordshire isn’t even a place you would typically describe as being well served in terms of data.

But this dataset brought me up short.

It’s a simple time series (well simple-ish) showing one number per year. That number is a measure of the affordability of housing in the county.

It’s a figure widely used which looks at the ratio of wages to house prices.

To measure wages. Now lots of people in Herefordshire each money and they earn wildly different wages. You need to simplify that spread of wages. You might normally pick the average wage, which is a widely understood way to summarise data. In this case they pick the lower quartile wage which is less widely understood but actually pretty straightforward. Average is the wage where 1/2 the wages earned are above that level and 1/2 are below. Lower quartile is the wage where 1/4 of the wages in the county are below that level and 3/4 are above that level. It’s a good measure of the sort of wages people on lower incomes earn.

To measure house prices. The approach to house prices is similar. There are lots of houses bought and sold and houses come in all sorts of different sizes. We look at the lower quartile price. The price where 1/4 of houses sold cost below that price and 3/4 cost more than that price.

So this is a measure of the ratio between house prices at the lower end to wages at the lower end. If house prices go up, the ratio goes up. If house prices go down, the ratio goes down. If wages go up the ratio goes down. If wages go down, the ratio goes up.

Or to put it another way smaller is better (assuming you think people should be able to afford houses).

And the affordability ration is not getting smaller.

There is a lot more data available about housing.

But really, how much data do you need?

The source data and many other interesting facts can be found on the LGA Inform website.