Tag Archives: Statistics

Lies, damned lies and social mobility statistics

A few days ago, when the government (and Nick Clegg in particular) was launching its  strategy for social mobility, there was a chart used that made me feel a little uneasy. I couldn’t initially put my finger on why that was the case, but it looked as if it supported the argument rather too well. The chart I’m talking about is reproduced below:

A problem of social mobility or regression towards the mean?

A problem of social mobility or regression towards the mean?

It was used to claim that initially better performing children from poorer families fall back compared with less well performing children from richer families as they get older and so justify action on social mobility. Without doubting for a moment that everyone should have equality of opportunity and be encouraged to be successful in life, somehow the chart looked a little bit suspicious to me.

Someone else had spotted a problem with it as well – a researcher from the business school at Warwick University. He pointed out what I’d been struggling towards recognising – it was more likely to be the result of a statistical phenomena known as regression towards the mean, rather than a genuine reflection of reality.

Regression towards the mean happens when you measure the performance of individuals at the extreme ends of two different groups. The most likely explanation for the pattern seen in the chart is that the good performances from both groups were over-estimates of the child’s ability. Over time, it’s therefore likely that a more realistic view of their performance is obtained through repeated testing – and this is never as good as their best performance that they were selected for right at the start of the process.

Similarly, those selected for particularly poor performances may just have been having an off-day (it happens with small children!) Over time, a more realistic view of their performance is also obtained through repeated testing – and this is never as bad as the performance that they were initially selected for.

Now, I have no doubt that the government’s social mobility strategy is needed and that the intentions behind it are honourable. But the misuse of statistics (and probably where no misuse is required) does nothing to further the cause of reform.

I could also argue that this incident provides a neat illustration as to why removing tuition fees and funding undergraduate courses at universities from general taxation to teach the sciences and social sciences should be seen as a priority …

16th April 2011

One further thing occurs to me this morning – how reliable is an assessment of a child’s performance on a test of ability or IQ at 22 months anyway? The methodological issues in undertaking such an assessment must be huge, be more a matter of subjective than objective measures and subject to a whole range of demand characteristics, from the expectations of the parents to the views of the  health worker performing the procedure.

It’s good to know that you’re out there – somewhere!

I promise that this is the final one of the series of posts (for now … as there’s always another quarter end …) which relate to my blog stats.

This time it’s a graph of the number of page views tenpencepiece.net has received every week since the start of 2009 (my first post was in November 2008 and the site moved here from wordpress.com during in October 2009.) The figures don’t include hits from the automated robots that Google and others send out across the internet to look for content to enable their search engines to work – these are pages read (or at least looked at) by humans (or dogs, perhaps!)

 

tenpencepiece.net - weekly page views 01-01-2009 to 03-04-2011

tenpencepiece.net - weekly page views 01-01-2009 to 03-04-2011

As I said, it’s good to know that you’re out there – somewhere!

 

Q1 2011 – Comings and goings

In case you weren’t bored enough already by the previous statistical post, here’s another. This time, it’s where people came from in the first quarter of 2011 and where they left to go to if they clicked on a link on this blog.

 

Q1 2011 - referring sites

Q1 2011 - referring sites

 

In some ways it’s no great surprise that facebook tops the list this time. I’m now finally on there myself and it also seems to have replaced a lot of the chatter that used to happen in the FirstClass forums in previous years. These are still there in second place, but it’s a very distant second place now. There have been very few direct visits from the OU Moodle forums too – again, no real surprise as I haven’t been particularly active on either the SD226 or DD307 forums and there’s no ability to set up a signature – so there’s no obvious place to leave a link to here.

 

Q1 2011 - clicks

Q1 2011 - clicks

 

There’s a much wider variety of places where people go to after visiting here though. The vast majority of them are clicks on the blogroll on the right hand side of the screen. Until a couple of months ago, these were listed alphabetically which obviously favoured ‘A BSc for me!’ I’ve since randomised their order and that seems to be levelling out the primacy effect to some extent. However, TMA Machine tops the list – an indication of what most OU students are thinking about most of the time!

If you’re not asleep yet, there will be a final post in this series once the week is over, showing the overall traffic here over the last two and a quarter years. Thanks again for visiting!

Most popular posts – Q1 2011

I had written an ‘April Fool’ post a few days ago that was scheduled to appear here just after midnight.

However, I read it again and decided it just wasn’t that funny. So it’s gone. As such, you’ll have to make do with a repeat (kind of) instead.

*Drum roll*

The graphic below shows the 30 most popular posts on this blog as voted for read by you, dear reader, in the first quarter of this year.

Most popular posts - Q1 2011

Most popular posts - Q1 2011

Here’s the repeat bit – these were the most popular posts in the same quarter last year:

 

Most read posts January - March 2010

Most read posts January - March 2010

 

As you can see, the most popular post from the first quarter last year would have finished a mere 9th.

The blog’s popular subject matter hasn’t changed that much, except it’s DD307 (red*) and SD226 (blue*) that’s the most popular topic (the bars are purple* to indicate a posts was about both), but some of the archived posts on DD303 (green*) still attract attention. The more general OU / higher education / student tuition fees posts (the yellow* bars) also figure quite highly.

Look – I know you may not be that interested in any of this. But it’s soooo much better than the “April Fool” joke post I’d written. Trust me.

And it also gives me another chance to say “thank you” to everyone out there who reads this stuff. Haven’t you got a TMA you should be writing? I know I have …

(*) Yes, I messed up. The colours are those on this year’s chart, and they’re different to last year’s. Hadn’t thought of that …

Never mind the quality, feel the width!

I’ve already posted three articles about my blog statistics for 2010. You may well be relieved to hear that this is the final one! This is simply a graph comparing the number of page views each week in 2010 compared with 2009.

2010 saw 53,501 page views (23,989 in 2009).

www.tenpencepiece.net - weekly page views in 2009-2010

www.tenpencepiece.net - weekly page views in 2009-2010

Unsurprisingly, given the OU examination timetable for ED209 and DD303, October was the busiest month with 13,479 views.

Thanks for visiting everyone – and I’m looking forward to (virtually) seeing you all again in 2011.

HOPEHIV fundraising and blog stats update, July 2010

Update: 1st November 2010

My justgiving page for HOPEHIV is now closed. If you would still like to donate to them, please do so directly at hopehiv.org


First things first. Thank you to those of you who have contributed to HOPEHIV through my justgiving page. The total donated at the time of writing stands at £80 (excluding gift aid). If you find the blog and my notes on ED209 and DD303 useful, there’s still plenty of time to donate if you wish to. It’s a great cause, and any sum – no matter how large or small – I know will be used to great effect.

The sponsored blogging has dried up a bit of late as I think that ebuzzing have had difficulties in getting UK advertisers into their programme. However, a couple of recent tweets from them suggest that this may change fairly soon, with new people being recruited into their UK operation. Even so, I’ve just claimed my first payment from them of €80.16, which will all go to HOPEHIV too.

ebuzzing sponsored blogging - status on 3rd July 2010

ebuzzing sponsored blogging - status on 3rd July 2010

The google ads on this blog continue to pick up a trickle of clicks – 102 so far – which amounts to 1 advertisement clicked for every 200 or so pages viewed on this blog. In theory, that’s raised another £29.66 so far, but, the total needs to reach £60 before I can claim a payment from them.

Google advertising - status on July 3rd 2010

Google advertising - status on July 3rd 2010

Thank you again to those who have donated so far. I’m going to keep my justgiving page open until 31st October 2010 and these contributions, plus everything I generate from sponsored posts and advertising before then will go to HOPEHIV.

So far this year, this blog has recorded a total of 19,480 page views. The graph below shows the weekly totals.

Weekly page views at www.tenpencepiece.net for the first six months of 2010

Weekly page views at www.tenpencepiece.net for the first six months of 2010

Far and away the most popular items on the site are the ED209 and DD303 chapter summaries I’ve created – the graph below shows downloads of these for the last quarter (March to June 2010).

Chapter notes downloads Q2 2010

Chapter notes downloads Q2 2010

Thank you too if you’ve provided a link to my blog – the chart below shows the top referring sites (excluding search engines) to here over the last quarter. A Student Again heads these stats (excluding referrals from my old blog and the OU forums).

Referrers Q2 2010

Referrers Q2 2010

Finally, those of you who did use a search engine to get here use these keywords the most. Unsurprisingly, given the nature of the bulk of the content of this blog, the top four keywords  in the last 3 months were dd303, ed209, dse212 and citp respectively. The chart below shows the top 25.

Keyword frequencies Q2 2010

Keyword frequencies Q2 2010

Thanks again for reading – and please keep posting your comments. They genuinely are a great encouragement to me.

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