Greetings from the City of Brotherly Love. Beautiful Philadelphia is awash with that late summer sunshine which I so confidently predicted last week was now finished for the year. Gone in Hackney it may well be, but Pennsylvania remains very warm. I would tell you the temperature but of course it’s reported in “F” rather than “C” and I have no idea what it means so I can never remember it. It’s hot – I’m wearing shorts. The shorts follow from the heat, not the other way round, by the way.

*

I enjoyed an afternoon drink in the Groucho Club in Soho last
Saturday, before I left for Philly. OK the truth is that I was at a
creative writing class there and I was drinking a glass of water, which
was the only substance we were allowed to consume, as non-members. Have
you ever been to a creative writing class? They are a great fillip for
winter months. There’s always the shocking moment when the girl with
the sweetest face and the quietest voice starts reading her homework: *You shut your f***** mouth you f***** f**** of a***** f***, he said, as she twisted the budgie’s neck.*
Even more embarrassing is when you introduce yourselves for the first
time. “My name is Graeme and I’m a statistician. From Hackney” I
announce, after listening to someone say “Hi, I’m a corporate lawyer,
I’ve had two plays produced on Radio 4 and I’ve just submitted my
second novel”. Anyway I labour on. It is surprising and a bit
frightening sometimes to read what you produce when you’re forced to
write without stopping for five minutes. Let’s hope no-one in our HR
department ever reads them.

*

Philadelphia is easily my favourite north American city (based on a sample of about 3, I should say, and one of the other two is in *North Carolina*). It’s funky in a sort of boho way guaranteed to appeal to Hackney types. There are men with tattooed necks. I saw some policemen smoking. It’s got yer real, actual history (the Liberty Bell lives here). The shops are cool. I went into Macy’s yesterday to look for some swimming trunks. There was a geezer playing a church organ, suspended from a wall about a mile off the ground. *Do you have any swimming trunks?* I yelled at the assistant, but she couldn’t hear me above the ear-shattering fugue from above. We smiled helplessly at one another, and I left without trunks. But if you are average – or even above – UK weight, then I guarantee you will come home feeling thin, thin, thin darling, even if you spend all week eating Philly cheesesteaks. That’s another thing I don’t have a clue about here. I got on the treadmill in the hotel gym, and it goes “enter weight in lbs”. What is lbs? I guessed at “300” and found to my joy that the machine then refused to let me “run” any faster than four miles an hour. (“What is *mile*?”). Exercise like this I can handle.

Now you might have noticed I’m supposed to write about politics, but that about this I often have problems. It’s now two weeks since I was in Britain and my lack of political insight is hourly more acute. If I were some sort of well-connected neocon, I could tell you the latest news from those throbbingly optimistic US thinktanks that the Editor is always visiting –* Lessons from the Iraqi Victory* – that sort of thing – but I’m more disconnected than well-connected, and more “old and shabby” than “neo” in my Toryism. So really I don’t know what’s agitating the US just now. There was a burglary in West Philadelphia yesterday, but I don’t think the Administration is being blamed. Some Iranian bloke was here too. *Didn’t wear a tie* I noticed, munching my granola this morning. Shocking.

So obviously I’m logging onto all the UK newspapers every day to keep up with the Labour conference and all that. Right. I did switch on the Telegraph website briefly, but I caught some headline – *"Brown 450 per cent. ahead of Conservatives in latest damning poll – the youth of Britain spontaneously marches down Whitehall singing “We love you Uncle Gordon, you are the saviour of our country”* – and switched it off again. There was a link to a page where someone rabid and unpleasant explained that the trick for the Tories would be to be more rabid and unpleasant, and that this would defeat Brown, but I gave it a miss. Advice to distressed Tory gentlefolk: it’s quite pleasant to spend Labour conference week on another continent.

*

Back home for a day. I can change my underwear faster than Superman these days. Two important observations: my friend Andrew Boff will not be the Tory candidate for London mayor. Never mind Andrew! I suspect your ideas – voters’ initiatives to clip the wings of the political class, and a relentless focus on giving local groups the power to improve their communities’ lives – will feature strongly in Boris’ platform. At least I hope so. *Unite to win* and all that.

Second observation. Gordon Brown and his team are monsters. I’m catching up with the newspapers now and the language used by Labour sickens me. Apparently Labour ministers are briefing the media that their conference was, quote, *about killing David Cameron and the Conservatives*; not the first time I’ve read the Labour leadership using the language of death. “Killing” the Conservatives? I see that Kinnock had a similar go earlier this week. What is wrong with these people? I’m not being intentionally rude, but their behaviour is sociopathic. This grim, dysfunctional clique have ruined this country for far too long. For heaven’s sake, will all those ultras on the right who seem to enjoy conniving with Brown please shut up now, and get on with fighting socialism? It’s bad enough looking at the starry-eyed “reporters” on C4 news blethering on about Brown and His Acts Of Greatness, seemingly forgetful about everything that’s happened since 1997, without having backbench MPs detract from our agenda next week. Note to MPs: if you use Blackpool as an excuse for reigniting a row about selective schooling, which the Brown-tongue media will use to spoil our conference week, be warned: an extremely angry activist from Hackney will *track you down* and bore you rigid over tepid cups of coffee. I can do no worse.

*

Back out to Verona and from there onto Blackpool. See you at the Tory Reform Group meeting on Sunday, comrades! I’ll end with a prediction. Brown will call an election sometime this coming week, most likely on the day of David Cameron’s speech.

Labour is definately obsessed with death and killing.

Just to bore you to death Graeme, one mile is 1760 yards, 5280 feet or 1610 metres. A pound is 16 ounces, and there are 14 pounds in 1 stone. A stone is 6.35kg and kilogram is 2.2lbs roughly. To convert Fahrenheit into Celsius, subract 32 from the degrees Fahrenheit and then multiply by 0.56 OR to convert Celsius to Fahrenheit multiply the Celsius by 1.8 then add 32. I learnt it in maths at a grammar school :-)

Have fun on the rest of your trip.

Posted by: David T Breaker | September 30, 2007 at 03:06 PM

This, dear readers, is the very same Graeme Archer who recently took me to the London Fields Lido one late summer afternoon, where he encouraged me to join him in his usual ONE MILE swim. We then joined friends to drinks CUPS of coffee and BOTTLES of red wine. He knows!

Posted by: Simon Walters | September 30, 2007 at 07:09 PM

Whilst you are in Blackpool I do hope you will take a stroll down the Golden 1.6 kilometres.

Posted by: Victor, NW Kent | September 30, 2007 at 09:33 PM

Highly entertaining as ever....

Graeme, I seem to recall reading an analysis you did of polling methodology some time back. The general approach was (I think but cannot be sure) to set out why different pollsters could not be compared and why, from a stats perspective, taking averages was meaningless. Do you have that posting somewhere to hand by any chance? If so, I'd be very interested to see it again.

(PS Sorry to ask such a dull question - your writing does inspire more interesting ones do not fear. It's just that I've been meaning to ask you for a copy of that posting for ages, that was all.)

Posted by: support the strivers | October 01, 2007 at 12:36 AM

Hello "support the strivers". I don't know where that post went, but I'll try and resummarise. It's a bit stats-y. For simplicity, consider the objective of using a poll to estimate the true support for the Conservatives.

Call the true level of support T.

Now, if any opinion pollster sampled completely at random - say they selected 1000 voters completely at random from the entire electorate - they would get an estimate - call it t - of T. t would not be equal to T, because it would be based on a sample and not the entire population.

Statistiicans write: t = T + e, where e is a random variable with zero mean and a variance - a standard deviation - which is a function of the size of the sample.

If the total number of electors is N and the random sample is based on n, then with probability 1 t -> T as n -> N.

If two pollsters produced estimates of Tory support in this way, giving unbiased estimates of tory support t1 and t2, say, then it would be completely admissable to construct a BETTER estimator of Tory support by averaging t1 and t2. Call this t3. Since t1 and t2 are unbiased, then so is t3, and it also has smaller variance. Thus it is a better estimator of T than either t1 or t2.

HOWEVER.

No opinion pollster produces an unbiased estimator of T, because none of them sample completely at random. This is a good thing, because to sample at random and get reasonable standard errors would require much larger polls than are carried out (the tradeoff between bias and variability is one of the fundamental mathematical theorems in classical statistical estimation theory).

So they deliberate introduce some bias into their sample. So a statistician might write the estimate t* from the biased poll as

t* = t + b + e

t and e are the same as above, but b is a systematic bias (I'm simplifying - any other statisticians reading - I would write b as the sum of a fixed and random effect term, with its own variance - but for simplicity am shoving that into e).

What this means is that as n -> N, we no longer have that t* -> T. Instead t* -> T + b. So no matter how many averages you take of this pollster's poll, you will not remove the systematic bias built into its construction.

The situation is, of course, worse if one does the following - as ConHome does, every bloody week - add together the estimates from different pollsters, all of whom use different methodologies and who therefore have different systematic bias terms in their estimates. Consider two pollsters giving t1* and t2* estimates of tory support. Using the same model as above, if you average t1* and t2* you get T + .5*(b1 + b2) as the expectation - i.e. a biased estimate, the bias of which we have no way of understanding.

So the manner by which ConHome constructs its poll of polls is flawed, misleading, biased and statistically degenerate. If an undergraduate statistician suggested it to his/her tutor, they would be marked down.

BUT. If we have two consecutive polls from the first pollster: t*1 and t*2 - and we assume - as I think is sensible - that the systematic bias in the same pollster's monthly polls does not change - then if we construct the DIFFERENCE between the two months we get:

t*1 - t*2 = T1 + b - T2 -b +e - e = T1- T2

In other words, the difference between consecutive polls from the same pollster is an UNBIASED (statistically sensible) estimate of the change in Tory support from month 1 to month 2.

If you did this for TWO pollsters you would have TWO unbiased estimates - and if you averaged these you would get, as we saw right back at the start, an ever better estimator (still unbiased but higher precision) than any individual one.

So the Conservative Home recipe should be as follows:

For each pollster, calculate the within-poll differnece in Tory support NOW and (say) 1 month ago.

Take the average between-poll of these differences.

This average would be an unbiased and highly precise estimate of the true CHANGE in Tory support over the last month.

cheers and cheers to Simon who is also a magnificent swimmer :-0)

Posted by: Graeme | October 06, 2007 at 04:14 PM