Damned lies and statistics

A closer look at statistics in the news

Kate Allen

If you’re going to have a bet this party conference season, take on an MP – that’s the obvious conclusion from an Ipsos Mori poll for the Royal Statistical Society, which suggests that our elected representatives are simply asking to be fleeced.

As part of its Parliamentary lobbying work, the RSS set a basic probability question for nearly 100 MPs. ‘If you spin a coin twice, what is the probability of getting two heads?’*

More than half of them got the answer wrong.

all MPs Read more

Emily Cadman

One of the more interesting aspects of Friday’s ONS release on the UK internet access patterns is the reasons why households don’t have internet access.

Much of the data release is as you would expect: more households have internet access, and more people are using computers daily, a trend especially noticeable among the young. Read more

Britain’s traditional measure of inflation, the retail price index, is broken and needs fixing. The error goes back decades, has cost taxpayers billions, is still costing the exchequer about £1bn a year and has resulted in the rise in living standards being underestimated. Few errors in statistical compilation are quite this serious.

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Chris Cook

One of my grand theories is that public policy types are generally bad at geography. Or, at the least, they underestimate the importance of where you live. Here, below the fold, are two zoomable maps, coloured by the school performance of local state-educated children. The map is based on where the children live, not where they go to school. To explain:

  • The colouring is red for weaker results and blue for better ones. Darker colours mean more extreme results. If you want detail on an area, click on any one of the blobs and it should give you a run down of local statistics, where possible.
  • Both maps are coloured according to FT score results: that is the sum of state-educated pupils’ scores in English, maths and their top three other subjects.    Other data, including official measures, are in the boxes that pop up.
  • On the first map, the geographical blobs are smaller than on previous maps: the lowest super output area in high density places, and the middle-layer output area in zones of low density (this way, we can show maximum detail).
  • That map can be quite frazzling. The second might be more to some people’s tastes. This is exactly the same sort data, just arranged by parliamentary constituency. Since they are bigger lumps, we can include more detailed data.
  • For the constituencies, I have given a barrage of results for all local children in state schools. But also the same just for FSM-eligible children, and for children dubbed “middle attainers” – kids who score in the middle tenth of results aged 11.
  • (NB – Where statistics are missing, it is prevent people combining data sources to work out something about individual children.)

If you want a tour, I’d recommend scrolling along the coasts. Check out some of the coastal towns, and look at the belt of towns and cities between Hull and Liverpool. Also, take a peek at how few dark red areas there are in London. In-borough variation is interesting, too: look at the massive variation within, say, Kent. Read more

Chris Cook

Since January, schools have been subject to a new inspection regime. Ofsted, the inspectorate, has changed its criteria. Data released today mean there is one question we can consider: is the new inspection regime any tougher or easier than its predecessor?

This is not a straightforward question: weaker schools get inspected more regularly, so the sample is not randomly selected. What we can do, however, is see whether schools are more likely to be promoted or relegated than in previous years.

This, too, is not simple. The Department for Education changed schools’ ID numbers when they became academies, so I cannot match every new report to the same school’s previous ones so it is a faff to match records, which has taken a bit of tinkering. We have matches for 1,711 schools – both primary and secondary.

Here are the results:

1 2 3 4
1 25% 50% 25% 0%
2 8% 58% 27% 7%
3 2% 44% 40% 14%
4 1% 13% 75% 11%

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Chris Cook

The cash advantage for converting to become an academy is bigger for schools in more affluent areas. Read more