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March 27, 2011

An informed decision

Caterham 7 vs Data Warehouse appliance - spot the difference

A friend and fellow information professional is currently responsible for both building a new data warehouse and supporting its predecessor, which is based on a different technology platform. In these times of ever-increasing focus on costs, she had been asked to port the old warehouse to the new platform, thereby avoiding some licensing payments. She asked me what I thought about this idea and we chatted for a while. For some reason, our conversation went off at a bit of a tangent and I started to tell her the story of an acquaintance of mine and his recent sad experiences.

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My acquaintance, let’s call him Jim to avoid causing any embarassment, had always been interested in cars; driving them, maintaining them, souping them up, endlessly reading car magazines and so on. His dream had always been to build his own car and his eye had always been on a Caterham kit. I suppose for him the pleasure of making a car was at least as great, if not more, as the pleasure of driving one.

It's just like Lego

Jim saved his pennies and eventually got together enough cash to embark on his dream project. Having invested his money, he started to also invest his time and effort. However, after a few weeks of toil, he hit a snag. It was nothing to do with his slowly emerging Caterham, but to do with the more quotidian car he used for his daily commute to work. Its engine had developed a couple of niggles that had been resistant to his own attempts to fix them and he had reluctantly decided that it was in need of some new parts and quite expensive ones at that. Jim had already spent quite a bit of cash on the Caterham and more on some new tools that he needed to assemble it. The last thing he wanted to do now was to have a major outlay on his old car; particularly because, once the Caterham was finished, he had planned to trade it for its scrap-metal worth.

But now things got worse, Jim’s current car failed its MOT (vehicle safety inspection for any non-UK readers) because the faulty engine did not meet emission standards. However, one of his friends came up with a potential solution. He said, ”As you have already assembled the Caterham engine, why not put this into your current car and use this instead? You can then swap it out into the Caterham chassis and body when you have built this.”

Headless Jim - with cropped face to protect his anonymity

This sounded like a great idea to Jim, but there were some issues with it. His Cateham was supplied with a Cosworth-developed 2.3-litre Ford Duratec engine. This four-cylinder twin cam unit was the wrong size and shape to fit into the cavity left by removing the worn-out engine from his commuting car. Well as I had mentioned at the start, Jim was a pretty competent amateur mechanic and he thought that he had a good chance of rising to the challenge. He was motivated by the thought of not having to shell out extra cash and in any case he loved tinkering with cars.

So he put in some new brackets to hold the Caterham engine. He then had to grind-down a couple of protruding pieces of the Duratec block to gain the extra 5 mm necessary to squeeze it in. The fuel feeds were in the wrong place, but a bit of plumbing and that was also sorted. Perhaps this might cause an issue with efficiency of the engine burn cycle, but Jim figured that it would probably be OK. Next the vibration dampers were not really up to the job of dealing with the more powerful engine and neither was the exhaust system. No worries, thought Jim, a tap of a hammer here, a bend of a pipe here and he could also add in a couple of components that had been sitting at the back of his garage rusting for years as well. Eventually everything seemed fine.

Jim ventured out of his garage in his old car, with its new engine. He was initially a bit trepidatious, but his work seemed to be hanging together. Sure the car was making a bit of a noise, shaking a bit and the oil temperature seems a bit high, but Jim felt that these were only minor problems. He told himself that all his handiwork had to do was to hang together for a few more months until he finished the rest of the Caterham.

Angular momentum = Sum over i : Ri x mi x Vi

With these nice thoughts in mind, Jim approached a bend. The car flew off the road at a tangent as he realised – too late – that he had been travelling at Caterham speeds into the corner and didn’t have a Caterham chassis, a Caterham suspension, or Caterham brakes. His old car was not up to dealing with the forces created in the turn. His tyres failed to grip and, after what seemed like an eternity of slow-motion spinning and screeching and panic, he find himself in a ditch; healthy, but with a wheel sheared off and smoke coming out of the front of the car. A later inspection confirmed that his commuting car was a write-off, and his insurance policy didn’t fully cover the cost of a new vehicle.

Jim ended up having to buy another day-to-day car, which delayed him from spending the additional money necessary to get the Caterham on the road for quite some time. However, after scrimping and saving for a while, he eventually got back to his dream project, only to find that combination of the modifications he had to make to the Duratec engine, plus the after effects of the crash meant that it was now useless and he needed to purchase a replacement.

So because Jim didn’t want to run to the expense of maintaining his old car while he built his new one, he would instead have to buy a new temporary car plus a new engine for the Caterham. Jim was just as far off from finishing the Caterham as when he had started, despite wasting a lot of time and money along the way. A very sad story.

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Suddenly I realised that I had been wittering on about a wholly unrelated subject to my friend’s data warehousing problem. I apologised and turned the conversation back to this. To my astonishment, she told me that she had already made up her mind. I suppose she had taken advantage of the length of time I had spent telling Jim’s story to more profitably weigh the pros and cons of different approaches in her mind and thereby had reached her decision. Anyway, she thanked me for my help, I protested that I hadn’t really offered her any and we each went our separate ways.

I found out later she had decided to pay the maintenance costs on the old data warehouse.


I would like to apologise in advance if anyone at Caterham, Cosworth, Ford, or indeed Peugeot, takes offence to any of the content of the above story or its illustrations. I’m sure that you make very fine products and this article isn’t really about any of them.


Filed under: data warehousing, project management Tagged: caterham, cosworth

Posted by Peter Thomas at 4:25 PM

March 2, 2011

I will be presenting at the IRM European Data Governance Conference

This IRM UK event will be taking place in central London from the 21st to 23rd March 2011. It is co-located with another related IRM conferences on Master Data Management.

My presentation will be entitled Making Business Intelligence an Integral part of your Data Quality Programme. Full details may be obtained from the IRM conference web-site here.
 


Filed under: general

Posted by Peter Thomas at 4:05 AM

March 1, 2011

Medical malpractice

8 plus 7 equals 15, carry one, er...

I was listening to a discussion with two medical practitioners on the radio today while driving home from work. I’ll remove the context of the diseases they were debating as the point I want to make is not specifically to do with this aspect and dropping it removes a degree of emotion from the conversation. The bone of contention between the two antagonists was the mortality rate from a certain set of diseases in the UK and whether this was to do with the competency of general practitioners (GPs, or “family doctors” for any US readers) and the diagnostic procedures they use, or to do with some other factor.

In defending her colleagues from the accusations of the first interviewee, the general practitioner said that the rate of mortality for sufferers of these diseases in other European countries (she specifically cited Belgium and France) was greater than in the UK. I should probably pause at this point to note that this comment seemed the complete opposite of every other European health survey I have read in recent years, but we will let that pass and instead focus on the second part of her argument. This was that that better diagnoses would be made if the UK hired more doctors (like her), thereby allowing them to spend more time with each patient. She backed up this assertion by then saying that France has many more doctors per 1,000 people than the UK (the figures I found were 3.7 per 1,000 for France and 2.2 per 1,000 for the UK; these were totally different to the figures she quoted, but again I’ll let that pass as she did seem to at least have the relation between the figures in each country the right way round this time).

What the GP seemed to be saying is summarised in the following chart:

Vive la difference

I have no background in medicine, but to me the lady in question made the opposite point to the one she seemed to want to. If there are fewer doctors per capita in the UK than in France, but UK mortality rates are better, it might be more plausible to argue that less doctors implies better survival rates; this is what the above chart suggests. Of course this assertion is open to challenge and – as with most statistical phenomena – there are undoubtedly many other factors. There is also of course the old chestnut of correlation not implying causality (not that the above chart even establishes correlation). However, at the very least, the “facts” as presented did not seem to be a prima facie case for hiring more UK doctors.

Sadly for both the GP in question and for inhabitants of the UK, I think that the actual graph is more like:

This exhibit could perhaps suggest that the second doctor had a potential point, but such simplistic observations, much as we may love to make them, do not always stand up to rigorous statistical analysis. Statistical findings can be as counter-intuitive as many other mathematical results.

Speaking of statistics, when challenged on whether she had the relative mortality rates for France and the UK the right way round, the same GP said, “well you can prove anything with statistics.” We hear this phrase so often that I guess many of us come to believe it. In fact it might be more accurate to say, “selection bias is all pervasive”, or perhaps even “innumeracy will generally lead to erroneous conclusions being drawn.”

When physicians are happy to appear on national radio and exhibit what is at best a tenuous grasp of figures, one can but wonder about the risk of numerically-based medical decisions sometimes going awry. With doctors also increasingly involved in public affairs (either as expert advisers or – in the UK at least – often as members of parliament), perhaps these worries should also be extended into areas of policy making.

Even more fundamentally (but then as an ex-Mathematician I would say this), perhaps the UK needs to reassess how it teaches mathematics. Also maybe UK medical schools need to examine numeric proficiency again just before students graduate as well as many years earlier when candidates apply; just in case something in the process of producing new doctors has squeezed their previous mathematical ability out of them.

Before I begin to be seen as an opponent of the medical profession, I should close by asking a couple of questions that are perhaps closer to home for some readers. How many of the business decisions that are taken using information lovingly crafted by information professionals such as you and me are marred by an incomplete understanding of numbers on the part of [hopefully] a small subsection of users? As IT professionals, what should we be doing to minimise the likelihood of such an occurrence in our organisations?
 


Filed under: business intelligence Tagged: mathematics, medical profession, numeracy, statistics

Posted by Peter Thomas at 3:22 AM