The Guardian newspaper in the UK often posts interesting data for its readers to mess with and comment on. The latest on the DataBlog (“where facts are sacred”) is a data set showing how the cost of raising a child has increased in the UK by 43% since 2003.
The data is from an insurance company, Liverpool Victoria. In neither this data article or the main editorial is the method of data collection described. It’s essential to describe this – A lack of visibility into methods, however reliable the reporting source, should quickly lead you to question the findings.
The other issue is that the costs don’t seem to have been adjusted to changes in the value of currency (be that through inflation or other methods). Any time monetary values are shown on a time-axis spanning more than a few months (under normal inflation values), the values should be normalized to a single point.
This is my take on the data using Tableau Public, I have presented both the non adjusted costs, and the costs adjusted using the UK’s consumer price index. The best normalization probably would be to median wage after tax, as these truly reflect the ability to pay for raising a child, but the CPI will at least give a more balanced view. You can see that the actual increase is about 22% from 2003, and that the only real contributors to this are childcare and education costs because they have increased the most above CPI, and they are the majority of the expenses. The problem with using CPI is that if you used a fine enough detail (e.g. the CPI of providing childcare), the results should, of course, be flat. This is why choosing how to deal with costs and time is far from straightforward.
Concerning my continued engagement with Tableau Public – it took a while to get the charts how I wanted them – I’m still on an enjoyable learning curve with the new software. There are a few bugs to iron out – for example it doesn’t handle null values in an expected way (treats them as zero) – maybe that’s still higher up on my learning curve..