Apr 08 2012

Bad polling

Bullied teachers fear culture of ‘macho managers’. Union survey shows 67% were affected by abuse and harassment from their colleagues

The Observer 08.04.12

This is the headline and subtitle to an article in The Observer today. Sound terrible doesn’t it? If I were working in an organisation where 67% of the staff were being bullied I’d probably want to leave, and I’d certainly expect senior management to be addressing the problem. Fortunately I suspect this headline is almost entirely misleading.

Firstly, the first line of the article says “more than two-thirds of teachers have experienced or witnessed workplace bullying in the past 12 months” (my emphasis) – so one teacher shouting at a colleague in a busy staffroom would generate an awful lot of “yes” votes.

Secondly, it’s described as an “online poll”, giving no information on the nature of the poll. If the respondents are randomly selected then fine, however if they are self-selected then it’s close to meaningless.

It’s possible that the level of bullying of teachers by their colleagues is at the level implied by the headline, but they’ve been done a great dis-service by their union and The Observer in the poor example of polling and reporting.

You’d have thought The Observer would have learnt its lesson by now, having published a mea culpa “When is a poll not a poll?” over a headline claiming “Nine out of 10 members of Royal College of Physicians oppose NHS bill” which highlighted exactly the issue with self-selecting surveys.

Apr 07 2012

Board of Longitude

It’s been a while since I did a data driven blog post, so here I am with one on the “Board of Longitude”. The board was established by act of parliament in 1714 with a headline prize of £20,000 to anyone who discovered a method to determine the longitude at sea to within 30 nautical miles. The members of the Board also had discretion to make smaller awards of up to £2,000 in support of proposals which they thought had merit. The Board was finally wound up in 1828, 114 years after its formation.

The latitude is your location in the North-South direction between the equator and either of the earth’s poles, it is easily determined by the position of the sun or stars above the horizon, and we shall speak no more of it here.

The longitude is the second piece of information required to specify ones position on the surface of the earth and is a measure your location East-West relative to the Greenwich meridian. The earth turns at a fixed rate and as it does the sun appears to move through the sky. You can use this behaviour to fix a local noon time: the time at which the sun reaches the highest point in the sky. If, when you measure your local noon, you can also determine what time it is at some reference point Greenwich, for example, then you can find your longitude from the difference between the two times.

The threshold for the highest Longitude award amounts to knowing the time at Greenwich to within 2 minutes, wherever you are in the world, and however you got there. This was a serious restriction at the time, because a journey to anywhere in the world could have taken months of voyaging at sea with its concomitant vibrations and extremes of temperature, pressure and humidity all of which have serious implications for precision timekeeping devices.

The Board of Longitude intertwines with various of the people whose biographies I’ve read, and surveying efforts taking place during the 18th and 19th centuries. It made a walk on appearance in Tim Harford’s Adapt, which I’ve just read, as an early example of prizes being offered to solve scientific problems.

Below I present data on the awards made by the Board during its existence from 1714 to 1828. The data I have used is from “Britain’s Board of Longitude: The Finances, 1714-1828” By Derek Howse1 which I reached via The Board of Longitude Project based at the Royal Museums at Greenwich. The chart below shows the cumulative total of the awards made by the Board (blue diamonds), awards made to John Harrison who won the central prize of the original Board (black triangles) and the dates of Acts of Parliament relating to the Board (red squares). Values are presented as at the time they were awarded, the modern equivalent values are debatable but the original £20,000 award is said to have been worth between £1million and £3.5million in modern terms, so a rule of thumb would be to multiple by 100 to get approximate modern values.

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Although established in 1714, the Board made no reward until 1737 and until 1765 made the great majority of awards to John Harrison for his work on clocks; clockmakers Thomas Earnshaw (1800, 1805), Thomas Mudge (1777,1793) and John Arnold (father and son 1771-1805) also received significant sums from the Board.

A second area of awards was in the “lunar” method of determining the longitude which uses the positions of stars relative to the moon to determine time and hence longitude. The widow of Tobias Mayer received the largest award, £3,000, for work in this area. The list of awardees contains a number of famous European mathematicians including Leonhard Euler, Friedrich Bessel, and Johann Bernoulli.

After 1763 the Board started to branch out, having been mandated by parliament to prepare and print almanacs containing astronomical information. In the twilight of its years the Board gained responsibility for awards relating to the discovery of the North-West passage (a sea route from the Atlantic to the Pacific via the north of Canada), the second largest recipient of awards for the whole period were the crews of the Hecla and Griper of £5000 in 1820 for reaching 110oW within the Arctic Circle, pursuing this goal.

The story of the Board of Longitude is often presented as a battle between the Board and John Harrison for the “big prize” but these data highlight a longer and more subtle existence with Harrison receiving support over an extended period and the Board going on to undertake a range of other activities.

References

1. “Britain’s Board of Longitude: The Finances, 1714-1828” By Derek Howse, The Mariner’s Mirror, Vol. 84(4), November 1998, 400-417. (pdf) Sadly the article notes that Derek Howse died after the preparation of this article.

2. Data from (1) can be found in this Google Docs spreadsheet

Apr 06 2012

Book Review: Adapt by Tim Harford

adaptThis is a review of “Adapt: Why Success Always Starts With Failure” by Tim Harford which puts forward the thesis that “trial and error” is the only way forward for complex endeavours to succeed.

Opening up to trial and error is divided into three tasks:

  • Providing scope for variation in what you do;
  • Establishing whether or not a variant has been successful;
  • Making sure that you have systems in place to cope with failure.

Each of these tasks is illustrated with a wide range of real-life examples: using the Iraq War to highlight the difficulties of running “trial and error” inside control structures that are designed to take in information, channel it to the top of the organisation and provide a channel back from the top to the bottom. Donald Rumsfeld, apparently, would not refer to the “insurgents” as “insurgents” so hobbling the US’s ability to fight an “insurgency”.

Alongside these major case studies are smaller ones, such as on Jamie Oliver’s school dinners which showed that feeding children healthy food at primary level led to measurably better outcomes in education and attendance than comparable groups not within the scheme, you can see the study here.

There is also a section on using a carbon tax to address anthropogenic climate change, this fits in as a way of making selection possible by providing a simple measure of “success”. Harford is scathing of the ”Merton Rule” which demands that new build of above a certain size generate 10% of their electricity onsite by renewable means. As put by Harford this means installing capacity rather than demonstrating capacity which has lead to the use of dual fuel systems (nominally able to take renewable fuel) that are ultimately only used with non-renewables so providing no benefit at all.

The Piper Alpha and Three Mile Island accidents are provided as examples of the importance of being able to fail safely, they didn’t or rather Piper Alpha didn’t – arguably Three Mile Island just about failed safely. This was linked to failings in the financial system where large organisations, such as Lehman Brothers failed in a matter of hours with administrators scrabbling around frantically to come up with a controlled-landing plan. This is failure at large scale, but there is also coping with failure at the personal scale. For example, using “Deal or No Deal” as a model system in which contestants can “lose” which changes their estimations of risk for subsequent play for the worse.

One issue with “trial and error” is that the proponents of any method are often so convinced of the value of their method that they feel it immoral to subject anyone to an “inferior” alternative in order to conduct a trial. This is highlighted with a story about Archie Cochrane, pioneer of the randomised control trial in medical studies. He had been running a study on coronary care, comparing home-based care to hospital care. This had met with some opposition, with medics insisting that the home-based arm of the trial was unethical because it was bound to be inferior. When results started to come in it turned out that one branch of the trial was inferior to the other – Cochrane misled his colleagues into believing it was the home-based arm that was inferior – they demanded that it should be closed down but were rather silent when he revealed that it was in fact the hospital-based arm of the trial that was inferior!

Harford also discusses funding for research, in particular that blue-skies research could not be valued because the outcomes were so uncertain, highlighting the success of the Howard Hughes Medical Institute which funds speculative biomedical research in the US. What he goes on to say is that the use of prizes is a way out of this impasse. Using as an example the Longitude Prizes, his presentation plays up the friction between Harrison and the Board of Longitude. The Academie Des Sciences also ran prizes but until recently the method had been out of favour for approaching 200 years. The recent revival has included things like the DARPA challenges for self-driving cars, Ansari X Prize, the Bill and Melinda Gates Foundation prize for vaccines and Netflix’s film selection challenge. These have been successful, however it’s difficult to see them finding more general favour in the academic community since the funding is uncertain and appears only after researchers have expended resources rather than receiving the resource before doing the work.

From a practical point of view “trial and error” happens in the private sector, if not within companies then between. In the voluntary sector it has taken some hold, for me some of the more compelling examples were by the “randomistas” studying the effectiveness of aid programmes. In the public sector “trial and error” is more difficult: there is less scope for feedback on the success of a trial – you can’t meaningfully count customers through the door, or profits made, so there is a need for proxy measures. Furthermore, the appearance of failure carries a high price in the political sphere. This is not to say it shouldn’t happen, simply that “trial and error” face particular challenges in this area.

I like the central thesis of the book, it fits with my training as a scientist; my field allows for more direct experimentation than a randomised trial but the principle is the same. It also has pleasing parallels with biological evolution, which Harford explicitly draws. The book is well referenced, in fact I hit the end unexpectedly as I was reading on a Kindle – I couldn’t “see” the length of the end notes!

Mar 25 2012

Book Review: The Great Arc by John Keay

TheGreatArcThis is a review of “The Great Arc: The Dramatic Tale of How India Was Mapped and Everest Was Named” by John Keay. This book does exactly what it says in the lengthy subtitle: describe the Great Triangulation Survey of India which was conducted in the first half of the 19th century.

It fits together with “Map of a Nation” by Rachel Hewitt and “The Measure of All Things” By Ken Alder. The former describes the detailed mapping of the United Kingdom by the Ordnance Survey, whilst the later describes the measurement of the Paris meridian by Méchain and Delambre. Of the three surveys the French one had been completed first at the beginning of the 19th century whilst the mapping of the UK was going on at the same time as the Indian survey.

The book is centred around the Great Arc survey originally proposed by William Lambton at the beginning of the 19th Century. Lambton’s aim was primarily to measure a meridian (a line of longitude), in the same manner as the Paris meridian in order to gain more information on the shape of the earth (geodesy). For his sponsors in England and the administration of India the survey served as a military and commercial exercise. Military action is often a spur to survey, since getting your troops and their equipment from point A to point B and ensuring they prevail over any forces they come across on the way is a high-value activity which is greatly assisted by the provision of accurate maps. Surveying is also invaluable when you are planning infrastructure such as roads, canals and railways.

The survey came a time when the British relationship with the area now known as India was changing from a trading one based on outposts to one in which the British took territory militarily. The Triangulation Survey was not exhaustive, it comprised a central spine (The Great Arc) running along the 78th meridian up through the tip of the Indian peninsular to the edge of the Himalayas with regular “cross-bars” running from West to East, towards the north an array of parallel meridians were also measure. (You can see a map here). The aim was to use this survey to constrain further local surveys.

The Great Arc survey was a great endeavour, taking 40 or so years in total, after Lambton died in 1823 George Everest took on the job of leading the project. Lambton seems to have been a pleasant sort of chap who went a little native, disappearing from the view of his sponsors. Everest, on the other hand, appeared to be a complete git – being abusive to most of his subordinates and apparently also winding up his superiors.

Much of the activity in the book is in common with that which took place during the surveys of France and the United Kingdom. Laying out base-lines: distances measured directly on the ground by means of rods or chains used to pin down the distances in the “triangulation” which is a collection of angular measurements at the vertices of an array of triangles. Once again the precision is impressive, two 7 mile baselines measured out 200 miles apart agree with the triangulation measurement to within a few inches. Angular measurements were made using a theodolite, Keay labels the one used in India as the “Great Theodolite”, which I thought was a term reserved for the Ramsden device used in the UK (we can’t all have a Great Theodolite!).

The Indian survey presented different challenges in the form of the wildlife (tigers, scorpions etc) but also disease. The rate of attrition amongst the surveyors, particularly as they traversed jungle was terrible. The book is not explicit about figures but in the later stages of the survey something like a thousand men were involved and a couple of hundred of those died of disease. Lambton and later Everest both suffered from recurring bouts of malaria.

The “discovery” of Mount Everest and the tallest peaks in the Himalayas was somewhat incidental to the main thrust of the survey. It had become clear in the first decade or so of the 19th century that the Himalayas were the tallest mountains in the world but their precise height was uncertain. Political difficulties with Nepal, their location far from the sea and their immense size meant determinations were poor. Indeed at the time of the beginning of the survey the height of Mont Blanc in Europe was only know to within a thousand feet or so of its currently accepted value. It wasn’t until 1856, after the Great Arc had been completed and Andrew Scott Waugh had taken over the survey that Mount Everest (known at the time as Peak XV) was measured and Waugh proposed Everest be its name. (Everest is apparently pronounced Eve-rest rather than Ever-est, and the man himself was very particular about this).

Put beside “Map of a Nation” and “The Measure of All Things”, “The Great Arc” is a nice, brief introduction to the theme of triangulation surveys and geodesy which covers measuring the height of mountains in a bit more detail than the other two.

The Great Arc survey, along with the French meridian survey fit together with the earlier French Geodesic Mission to Peru by Condamine and Bouger around 1735, which is described in “Measure of the Earth” by Larrie G. Ferreiro – I’ve added this to my wish list.

Footnotes

You can see my Evernotes on The Great Arc here.

Mar 18 2012

Book Review: Decoding the Heavens by Jo Marchant

DecodingtheHeavens“Decoding the Heavens” by Jo Marchant is the story of the Antikythera Mechanism, a mechanical astronomical calculator dating from around 100BC which predicts the motions of heavenly bodies including the sun, moon and various planets. The best way to understand how the device worked is through videos relating to this book (here) and, rather more slickly (here).

The Antikythera Mechanism was recovered off the coast of the island which provides its name in 1900. The wreck from which it was recovered was also carrying a large number of impressive bronze and marble statues, for example the Antikythera Ephebe. It is believed it was sailing from the Asia Minor coast to Rome, carrying the spoils of war. The wreck lies at a depth of 60 metres which is deep for the technology available at the time, the distinctive metal-helmeted diving suit. It was discovered by the crew of Captain Krontos, who were sponge-divers. As such they did a very risky job, Marchant reports that between 1886 and 1910 around 10,000 divers died from the bends and a further 20,000 were paralysed.

Once they had discovered the wreck they reported it to the Greek government who organised the salvage operation, at the time it was one of the first marine archaeological salvages – it was preceded  in 1884 by a speculative operation in the straits of Salamis which had recovered little. By the 1950s hundreds of wrecks were known in the Mediterranean. Marchant states that this is the first ever attempt to salvage artefacts from a sunken ship, I’m sceptical of this claim – it’s only true for very narrow definitions of each word – Edmond Halley, for example, had a company offering to salvage treasure from sunken ships in the 1690s.

It is curious how little regarded the Anthikythera Mechanism has been over the hundred or so years since its discovery. A measure of this is that the Athens National Museum, where it is kept, were still finding bits of it in 2005! This re-discovery is in some sense understandable, the Mechanism presents a rather unassuming appearance when compared to the statues with which it was found furthermore curating appears to have sharpened its act up over the years. A second reason is that it almost has the air of a fake about it, no other mechanism of comparable complexity was known until around 1000AD, and there was little written evidence for the existence of such devices.

The book works through the interpretation of the mechanism chronologically by researcher, starting with the initial interpretations made by John Svoronos and Pericles Rediadis (1903), Konstantin Rados (1905), Albert Rehm (1907) and John Theophanidis (1934). These are covered quite briefly. These initial studies were based on an exterior view of the fragments and small amounts of visible text, of which more became visible as cleaning attempts were made. It’s worth highlighting here that the mechanism was covered in text, both labels and operating instructions although originally little of this text was discernable. From these studies the mechanism was related to astronomical equipment such as the astrolabe, but was clearly different since it had a more complex clockwork-like mechanism. This chronological approach means that the reader gets a fragmented view of the device (with reverses in interpretation), as the story unfolds. There is also a degree of dramatisation of the story (e.g. “Shit,” said Roger Hadland) scattered through the book, I must admit to finding these rather grating but they are relatively sparse.

After the initial investigations there was a hiatus, with interest appearing to restart in the 1950s possibly spurred by a visit by Jacque Cousteau to the wreck in 1953. Derek De Solla Price was the next to attempt an analysis aided by x-ray imaging of the mechanism which was not available in earlier times. Price was Professor of the History of Science at Yale, in addition to his work on the Antikythera Mechanism he also did early work on scientometrics and the Japanese atomic bomb effort. He finally published his analysis in “Gears from the Greeks” in 1974, this included a detailed description of how the mechanism might have operated based on the gearing made visible by x-ray imaging.

The next attempt at a reconstruction was made by Michael Wright, originally curator of the engineering collection at the Science Museum in work starting in the early 1980s. He was joined by Allan G Bromley, a computer scientist and historian who was also involved in the reconstruction of the the Babbage. They quickly realised that Price’s theoretical reconstruction was in places somewhat creative. Wright ultimately produced a physical reconstruction of the mechanism over a period of 20 or so years.

Most recently, commencing in around 1998) there has been a collaboration led by Mike Edmunds at Cardiff University (The Antikythera Mechanism Research Project). They were able to bring to bear better x-ray tomography which was even able to reveal the details of inscriptions inside the accreted masses of the mechanism fragments, alongside Polynomial Texture Mapping, a photographic technique utilising multiple lighting angles and reconstruction to provide maximum information from surface markings. With collaborators at the Athens Nation Museum they also had access to an additional major fragment which had recently been discovered. Their work was published in the journal Nature (here in 2006 and here in 2008).

The comparison between the Wright and Edmunds collaborations is intriguing, in terms of scientific prestige the Edmunds collaboration have published on the mechanism in Nature the premier general science journal. They are a large collaboration with the best equipment, and fit well within the conventional scientific context. Wright, and to a lesser extent Bromley, were different. Wright in particular comes over has being very hard done by in the process, working in his spare time on the mechanism, always apparently “junior” to Bromley (the formal academic) and ultimately being pipped to glory by the Edmunds collaboration. His story comes through because Marchant has clearly interviewed many of the participants, rather than relying on the published literature. From the point of view of the published literature, all that is really visible to the scientific world, Wright’s efforts were virtually invisible until long after he had started work on the Mechanism.

The “problem” for the earliest interpreters of the mechanism is that it was so utterly different from anything else available from the period. There were no other clockwork like devices and few mentions of them, indeed the next instances were thought to be around 1000AD – it looks like the Antikythera Mechanism was dropped into the past from elsewhere. Nowadays it can be seen that this isn’t true. Archimedes and Ctesibius had been making complex mechanical devices in the 3rd century BC, although there are no physical remnants and the written records are sparse. On the other side, mechanisms of this type were in existence through to 1000AD and from then clocks appeared very rapidly suggesting a pre-existing store of knowledge.

In ancient Greece it is believed there were hundreds of thousands of bronze statues, the number left today are in the hundreds, at most. What chance even a few hundred rather unassuming objects to survive? As for the written record, what survives from the period has been repeatedly transcribed to suit the prevailing conditions, and they did not seek detailed descriptions of recondite mechanics. Can you lay your hands on the blue prints for an NMR machine?

The Antikythera Mechanism would have been made on the basis of the astronomical observations of the Babylonians who preceded its Greek makers. They had no “mechanical” model of the motions of the stars but they had a long, deep observational record of their movements. I’m interested in the night sky, and I can’t tell you but the details of the phases of the moon, even where it rises and sets let alone the motions of other planets are a mystery to me in the intuitive sense (I know I can look them up). The ancients had little to do at night, other than look at the sky – I feel I’ve lost something through having so many distractions and a night sky obscured by light pollution.

Footnotes

My Evernote on the book contains page by page comments, and also some links to related material