Archive for the 'science' Category

Fun with Polarization


I went to see Toy Story 3 in 3D (great film, but the 3D was not worth it); so I have a pair of those cheap plastic “3D” glasses.

They’re actually polarising lenses (er, filter, not lens, as the picture is not magnified or minified, but whatever). You can use them to Do Science at home:


Above is a picture of an iPod taken through one of the lenses (of the 3D glasses). The coloured pattern is, I think, due to birefringence, but I’m not competent to explain it entirely.

Same shot, but using the other lens:

So we see that the lens can be used to see patterns that are otherwise not visible. In this case, we can see stress patterns in the plastic (I think). Looking a bit more carefully at the iPod pictures, we can see that the patterns on the iPod are different for the two lenses. Thus, there are two different sorts of light that each lens passes.

The next picture involves a mirror:

I am holding the camera behind one of the lenses and shooting a picture into the mirror so I can see myself and the glasses and camera in the mirror. [edit: it’s more fun to put the glasses on and look into a mirror and close one eye, but I can’t show you a picture of that.]

Note that from the viewer side both of the lenses in the glasses are transparent. But as seen in the mirror, one of the lenses is opaque. Curiously the lens that is opaque in the mirror, is the one in front of the camera. How did the picture get taken!? Clearly light is able to enter the camera having passed through the right-hand lens. But the camera, behind the right-hand lens, is not visible. So light leaving the body of the camera through the right-hand lens cannot pass through the lens again when reflected in the mirror:

My explanation of this is that the light acquires a property as it passes through the lens, and the mirror changes that property so that light with the new property cannot pass through the lens. The property is the handedness of circular polarisation. The right-hand lens filters the light so it contains right-circular polarised light (say); the mirror reflects it into left-circular polarised light which cannot pass back through the lens (and into the camera sensor). Note that light that passes through the left lens and is reflected in the mirror, can pass through the right-lens.

[edit: however, I have a problem with this explanation, as it does not explain what happens when I get my laser pointer out…]

3D films work by displaying one frame through a left-circular polarising filter, and the next through a right-circular polarising filter, and alternating. A reflective screen with the right properties will maintain the separate polarisation of alternate frames. Circular polarising filters in the glasses are insensitive to viewing angle, so it’s a superior option to linear polarisation.

Colouring Doubt’s Flag


Judith Curry is keen to frame doubt in the form of an italian flag. Specifically with reference to this statement from IPCC WG1 Summary for Policy Makers:

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.

Curry’s flag interpretation of this statement is that we could colour the flag 5% white (uncommitted belief), 67% green (anthropogenic forcing), 28% red (natural variability). A minor quibble: the opposite of “due to increase in anthropogenic GHG” is not “natural variability” as that excludes other anthropogenic activies such as sulphate emissions and secondary effects like ozone increases due to Montreal protocol. Anyway, her flag would look like this (if she drew it):

Does that seem right, can we be almost certain that there is only 5% wiggle room for doubt? Also, if I say that 70% of the variation is anthropogenic that doesn’t mean the rest (or almost all the rest) is natural, it just means I don’t know. I interpret the IPCC statement as meaning that there are a wide range of supportable beliefs about the anthropogenic cause of 20th century warming, but 95% (ish) of those will have more than 50% of the flag coloured green. Amongst the population of possible flags is this one:

Note that this flag already represents quite an extreme position with respect to the IPCC statement, because whilst it’s compatible with the IPCC statement, only 5% of the flags have a smaller green area than this. Here’s a more median position:

How can we represent the range of beliefs that are compatible with the IPCC statement. Like this?

Warning: Generation Green could be in a classroom near you!


British Gas sent me a link to Generation Green. A classic greenwashing move: they seem to have paid a charity to produce a load of “green” lesson plans as a way to get their trademark embedded into every classroom, and therefore also into the minds of every future energy consumer. Leaving aside, for now, the ethics of corporate sponsorship of the classroom (hint: it’s wrong), what is the content like?

I had a look at Lesson 4 – Exploring sources of energy (part 1). One of the resources for this lesson is the “Energy Source Information Cards”: a series of 10 cards, one for each source of energy (coal, nukes, wind, and so on). There’s a Word document containing these that you can download (lower right of the web page I linked to).

It is from these cards that the students will be taking the factoids and copying them onto their posters in colourful crayon so that the posters can be displayed on the corridor walls in time for the first parents’ evening of term.

So, how are they? Well, a bit poor. On the whole, I’m a bit disappointed that “facts” like these are getting fed to children (and, more worryingly, their teachers). The perfect antidote to this generationgreen nonsense would be to use David MacKay’s book, Without Hot Air (go on, it’s free!). The chapters are bite-sized (especially the earlier ones), and they contain facts, and references, and good stuff.

The howlers in the “Information Cards” are Wind (mechanism wrong way round), Biomass (written by two people that never saw each other’s work), and Wave (written by someone who has no idea where the energy in waves is).

Overall there is a confusion between power and electricity. Every card has a section on how electricity is generated using that source. The Natural Gas card points out that gas can be piped into people’s homes, but there’s no mention of the fact that this is then used for heating not electricity generation. Coal, gas, oil, and biomass can be used more efficiently for heating applications directly than via conversion to electricity, but this is never mentioned. Nor is the fact that this is only of limited use because we only exploit a limited amount of low-grade heat.

There is also confusion about cost. Sometimes high capital cost (hydro) is mentioned, sometimes it isn’t (nukes). Often zero running cost is mentioned (wave) without mentioning capital. The important cost, total cost per kWh over the entire lifetime of the plant, is never mentioned.

There is also some confusion about pollution and global warming. Pollution is bad, global warming is bad. But these things are completely separate. There’s a tendency in the cards to assume that anything emitted into the air is bad, because of global warming and pollution; they’re not always specific enough about which it is.

Perhaps you can pick a different lesson and mock that, then at the end we can collect all our answers together and have a chat and make a nice poster?

Page 1 – Traditional Coal

This card is basically fine. The only things worth mentioning:

“Hard black substance that is found buried deep underground.”

Coal is not always hard (anthracite is, but it’s not the only form of coal), and it’s not always buried deep underground (I have picked it up on beaches).

Page 2 – Natural Gas

Basically fine.

Page 3 – Crude Oil

Typo: “most well knows” should be “most well known”.

There’s a double count in the disadvantages: “Burning oil pollutes the air”, and “Burning crude oil produces other emissions e.g. sulphur dioxide”. The “other emissions” are the pollution from burning oil. Perhaps better would be “Burning oil pollutes the air with sulphur dioxide and other emissions” (as does coal, by the way).

Page 4 – Wind Energy

“Wind is the effect of air flowing from low pressure to high pressure.” No, no, no, no, no. Bzzt. You’re wrong. Following is “The air in the warm regions rises and the cool air rushes in to replace it and this is what we know as wind”. A somewhat simplistic explanation, but that’s okay. The “this” is a horribly ambiguous reference; “this movement of air” would be better.

“As one of the windiest countries in Europe, it is perfect for our climate”. Yes, assuming we want to carpet bomb the British Isles with wind turbines. David MacKay’s ludicrously optimistic sketch of using 1/3 of our offshore coast for wind power (including uneconomical deep offshore wind) and carpeting 10% of our land (!) with onshore wind gives 58 kWh/day per person, or nearly half of the UK consumption. Perfect.

“Once it is built the fuel costs nothing”. Not true: offshore wind turbines need frequent replacement of the gear boxes due to sea-salt corrosion (and this should go in the disadvantages section).

Page 5 – Geothermal

Basically fine.

Page 6 – Biomass

In advantages: “It supports farmers because they can sell their crops for biomass fuel”. Whilst this is true it is seems silly to single out farmers. An advantage of wind energy is that it supports turbine blade manufacturers because they can sell their turbine blades as parts; an advantage of crude oil is that it supports oil drillers because they can sell their oil for fuel. It’s just a silly argument. What if crack cocaine was a fuel, would we be saying “it supports drug dealers because they can sell their stash for fuel”?

The “advantages” contradict the “disadvantages”. “Biomass fuel tends to be cheap” versus “Biomass can be relatively expensive compared to other sources of energy”. “Burning biomass produces carbon dioxide gas which contributes towards global warming”, strictly true but as the same card explains in the “advantages” section: “Although carbon dioxide is released when biomass is burned, it is still a carbon neutral source of energy. The amount of carbon dioxide that is released when biomass fuel is burnt is the same as the amount of carbon dioxide absorbed by the plants when they were growing.”

Page 7 – Uranium

“It does not contribute to the greenhouse effect because it does not produce smoke or carbon dioxide”. Mentioning “smoke” is absurd. The smoke produced by other sorts of power generation does not contribute to the greenhouse effect, quite the opposite. Smoke is an aerosol that has a cooling effect. Smoke is of course a pollutant, so nukes avoid air pollution, which is worth mentioning.

In advantages: “It produces small amounts of waste”. True, but so misleading. They make up for it in the disadvantages.

“It is not renewable; when the uranium is used it can not be replaced”. True, but worth mentioning the possibility of sea-dissolved uranium, which is replaced (er, I think).

“It is very difficult to turn off a nuclear power station”. Again, true, but it would be good to say a little bit on why this is a disadvantage. The reason it’s a problem is that no-one wants electricity at night but the nuclear power stations generate it anyway; you have to throw it away.

Page 8 – Solar Energy

“Every second, the Sun turns millions of tonnes of hydrogen into energy”. Well intuitively this didn’t seem right to me, but it turns out to be both right and wrong. The sun converts mass into energy at the rate of 4.4e9 kg per second (or 4.4 million tonnes, if you’d rather), and of course that mass is hydrogen. But it’s a little bit misleading not to mention the 600e9 kg of hydrogen that get converted to helium in the process. In other words every second, the Sun turns 600 million tonnes of hydrogen into helium, producing some energy in the process.

Only talks about PV, doesn’t mention solar concentration electricity generation such as the 11 MW PS10 tower in Spain (warning, EU press release).

Page 9 – Hydroelectric Energy

Hmm, it says here “Solar power can be used to create electricity in remote places where it might be very hard to get
electricity through cables”. Oh rly? What’s that got to do with hydro? Nothing, that’s what. Cut-and-paste hack-job.

Then the voice changes. Suddenly we see “we”: “We can control when the electricity is made by opening and closing the dam gates.”, and “Electricity can be generated 24 hours a day as long as we have the water”. It just hasn’t been proofread.

Disadvantages: “It is very expensive to build a dam”. Oh rly? Well, it is very expensive to build a nuclear reactor, and very expensive to build a wind farm the size of Wales, but you didn’t seem to mention that. Just casting about for disadvantages were we?

Another disadvantage: “There can be negative environmental impacts as water quality and quantity downstream can be affected and have a knock on effect on wildlife”. True, but there can be a positive effect on wildlife as well, as water habitats are created upstream of the dam and they are exploited by suitable species.

Page 10 – Wave Energy

“Wave energy is harnessed from the movement of the surface water of lakes, rivers and oceans.” Wrong. Should read “oceans” for “lakes, rivers, and oceans”. You cannot get usable energy from a wave on a lake. And as for rivers, stop laughing at the back. “Turbines can be placed by the shore, where the movement is at its strongest.” The latter bit, “where the movement is at its strongest” seems like a dubious claim to me. Surely the Atlantic waves have just as much movement a few miles offshore? The advantage of shore placement is shorely (sorry!) shorter cables?

“The wave acts like a piston that pushes air up and down an oscillating water column.” Well, that’s one way to get energy out of a wave, and it’s (kind of) how the Islay LIMPET works, but there are many other ways. Pelamis works by using the flexion of a linear body floating on the surface to drive hydraulic rams. CETO works by having a submerged buoy drive a piston to pump seawater inland at high pressure which then drives generating turbines. Salter’s Duck works, as far as I can tell, a bit like a self-winding watch.

“As an island we have lots of access to the coast and therefore could harness a lot of wave energy.” Yeah man, a lot of energy. According to MacKay, the total Atlantic wave energy hitting Great Britain amounts to 16 KWh/d per person or about 1/8 of our total consumption. If we exploited all of that then the Newquay tourism industry would be very annoyed (a disadvantage not mentioned, incidentally).

“It can be unreliable because it depends on the waves – sometimes you’ll get loads of energy, sometimes nothing”. Ah, no. Wave power is about the most reliable source of energy derived from a moving mass. Thousands of kilometres of Atlantic fetch can’t be wrong. There are always waves.

“Some designs can be very noisy”. Surely bogus, because no-one is proposing living next to them. Visually distracting, maybe, and a menace to fishing and shipping, but those disadvantages aren’t mentioned.

That’s all folks! Don’t forget your homework now, pick a lesson and tear it apart!

BBC: remove errors bars for better headline


In this article from the BBC Richard Black claims “This year appears set to be the coolest globally this century”. There is no basis for this claim, and moreover the very notion of picking warmest and coolest years amounts to bickering about global warming.

Black appears to be making this claim on the basis of looking at column 2 of the HadCRUT data. Here’s a graph, freshly minted from the Google Chart API:

The data is taken from HadCRUT, here’s a relevant extract:

2000  0.238  0.249  0.227  0.333  0.144  0.238  0.233  0.334  0.143  0.334  0.143
2001  0.400  0.411  0.388  0.495  0.304  0.400  0.394  0.495  0.304  0.495  0.303
2002  0.455  0.466  0.445  0.553  0.358  0.455  0.450  0.553  0.358  0.553  0.357
2003  0.457  0.468  0.447  0.556  0.359  0.457  0.452  0.556  0.358  0.556  0.358
2004  0.432  0.444  0.421  0.530  0.335  0.432  0.426  0.530  0.334  0.530  0.334
2005  0.479  0.490  0.469  0.580  0.378  0.479  0.473  0.581  0.378  0.581  0.378
2006  0.422  0.432  0.412  0.517  0.327  0.422  0.416  0.518  0.326  0.518  0.326
2007  0.404  0.414  0.394  0.501  0.307  0.404  0.398  0.502  0.307  0.502  0.307
2008  0.281  0.292  0.270  0.428  0.134  0.281  0.275  0.429  0.134  0.429  0.134

The format of the data is described here, by Hadley.

In the graph the red line is the best estimate, the pink lines shows the combined 95% uncertainty from all sources. You can get more, or possibly just different, graphs from Hadley.

The first thing to notice is that Black’s claim is false if you include the year 2000. Okay so technically I know that “this century” starts in XX01 but I also know we all celebrated the beginning of the millennium in 2000 and we accepted then that although 2001 was technically the beginning of the millennium (and hence the century) it was much hipper to celebrate 2000. So that deserves a mention at least.

But really my gripe is about not observing the error bars. The uncertainty in the data is such that the error bars all overlap! The data does not support the claim that 2008 is warmer than 2005 for example; if we take as our null hypothesis that these two years are the same temperature then we cannot reject it with any confidence. The same is true about any other pair of years (except possibly for 2005 versus 2000; we might be able to claim that 2005 was warmer than 2000).

Neglecting 2000, as Black obviously does, the data are consistent with a constant anomaly of +0.4°C. That’s just an example, many other temperature series would be consistent with the data, including ones which make 2005 the coolest year.

And that’s the problem with trying to “rank” years. The uncertainties in the data are all so large compared to the yearly changes that it’s totally meaningless to talk about the warmest year or the coolest year. We just don’t know.

Of course, if Richard Black had thought about the uncertainties in the data then he would’ve had to say “latest HadCRUT data shows 2008 about as warm as any other year this century”, and that’s not a very controversial thing to say. All this dramatic concentration on the yearly, monthly, daily ups and downs of global temperatures, greenhouse gas levels, what-have-you is nonsense. It’s just talking about the weather while the planet burns.

DEFRA promotes bovine TB in herds


Farming Link is a magazine published by DEFRA. I assume it is sent to all DEFRA registered farmers (in the UK in order to receive money under the Single Payment Scheme you must be the registered owner of entitled land; DEFRA probably uses this list or something similar).

August’s edition is hot off the press and contains an article that introduces the gamma interferon test (for bovine tuberculosis). This article correctly identifies the major benefit of the gamma interferon test, namely higher sensitivity compared to the skin test. Sensitivity is the proportion of infections that are identified as positive according to the test. So the gamma interferon test correctly identifies more infections than the skin test. The appendices of Specificity Trial of the BOVIGAM® IFN-Gamma Test in GB Cattle give a sampling of figures for sensitivity: around 77% for skin test; around 88% for gamma interferon.

Currently in some situations it is up to the farmer whether a herd should be tested using the more sensitive gamma interferon test or the traditional skin test. Carl Padgett, president of the British Cattle Veterinary Association, is quoted as saying “If you have a herd with a brand new infection, you want to get rid of that infection as quickly as possible before it spills over to neighbouring farms or into the local wildlife population. So you want to take out as many animals as possible that might be infected rather than keeping them in the herd”. Sounds like jolly good advice to me.

But then the article goes on to say that in some herds with recurrent TB problems “the [gamma interferon] test may pick out more infected cattle than the standard skin test”. Well yeah, it’s more sensitive, that’s what it’s supposed to do. The articles says that in these circumstances the gamma interferon “might not be in the farmer’s interests”. In other words DEFRA is saying that because the skin test leaves more infected animals in the herd it could be better for the farmer; the farmer will have to replace fewer heifers (expense) and therefore should opt for skin test. In any case I don’t really buy the expense argument. Animals that test positive are compensated for at the market rates, isn’t there an equivalence between money and heifers? Isn’t this what economics is about?

What is DEFRA’s agenda here? Reducing bovine TB, or minimising the number of positive animals it has to purchase?

My 2p’s worth


My 3⅓ year old nephew was playing with a magnetic construction kit (rods with magnets on both ends, steel balls; you’ve probably seen them); I was helping. We were testing which materials were magnetic and which were not. His naïve understanding seemed to be that metal things would stick to the magnet and other things (skin, plastic, cardboard) would not; except for the toy cat, which has fridge magnets in its feet so obviously would stick. I tried to surprise him by showing him some coins and asking him whether he thought they would stick to the magnet. “Oh yes” he said. I was the one that was surprised when a 2p coin stuck to his “magnet crane”.

It turns out that “copper” coins from 1993 stick to magnets; those produced up to 1990 do not. And evidently I’ve stopped playing with magnets or I would’ve known this simple fact.

Bet that’s not on the AQA Physics exam.

Secrets of Reducing Your Carbon Footprint


Can we grow willow and bury it?

This carbon footprint article from The Independent reckons that the average Briton’s carbon footprint is 10.92 tons of CO2.

This article about phytoremediation in Sweden suggests short rotatation coppicing gives a yield of about 6-12 tonnes of oven-dried willow per hectare per year. Similar yields in England are suggested by the survey results that I got Ian Tubby of the Forestry Commission’s Biomass Energy Centre to e-mail me. Optomistic rule of thumb: 10 tonnes of willow per hectare per year.

Willow is about 50% carbon. So from one hectare we can sequester 3-6 tons of carbon.

That seems like a long way off the 10.92 tons of CO2 that we’re each responsible for producing. But hold onto your apples and oranges there. A little bit of chemistry reveals that 1 ton of carbon is equivalent to 3.67 tons of CO2. That’s because carbon has atomic weight 12, but CO2 has molecular weight 44 (12+16+16), so every 44 tons of CO2 has only 12 tons of carbon in it.

So our 10.92 tons of CO2 per year is only 2.98 tons of carbon. Which we can easily offset with 0.6 hectares of willow or so. Of course to actually offset the carbon we need to bury the willow. In a hole in the ground. Like maybe a coal mine. (And how do we replace the P, N, and K that I’ve just buried?)

Of course as well as sequestering carbon to offset my footprint I could displace carbon. Instead of burning coal (geological carbon) I could burn willow. This leaflet from some random consultants suggests that 0.7 hectare of willow is sufficient to heat a 3 bedroom house.

Anyone know the average number of KWh per year it takes to heat a house in the UK? It’s surprisingly hard to find the answer in anything approaching an SI unit. This so obviously transient page (referenced on 2007-04-20) links to dataset ST341114 from the Office of National Statistics. That gives a 2001 figure of 1210 for space heating and 450 for water heating. Per household. The units? Why, kilograms of oil equivalent of course (haven’t these guys heard of SI?). Which Wikipedia suggests is a bit of a variable quantity; 1 kilogram of oil equivalent could be 42, 41.868, or perhaps 41.85 MJ. Really I only need a rough guide. Call it 42. That’s 69.72 GJ per jear.

Plausibility check: I burn about 1.2 tonnes of anthracite a year, plus some electricity to heat water in the summer. Anthracite has calorific value of 36 MJ kg-1 so that’s 43.2 GJ plus the electricity. So we’re in the right ball park. An even cruder check would be that 1.2 tonnes of coal is surely about the same amount of heat as 1.2 tonnes of crude. This time I’m thankful that the ONS uses silly non-SI units.

Seasoned wood has a calorific value of 16 MJ kg-1. The average household will need 69.72/16 = 4358 Kg of seasoned willow. About 0.5 hectare then (and a 5-year lead time (3 for growing up to the first harvest, 2 for seasoning), eek!). So the random consultants are in the same ball park with 0.7 hectare. There are 2.4 people per household so we only need 0.2 or 0.3 of a hectare per person to displace the carbon we were using for heating (which, according the The Independent article, is .40 tonnes). The lower calorific value of willow (compared to anthracite or crude) means we need to grow more willow, but we end up burying less.

So by swallowing a few assumptions, I personally could make myself carbon neutral with less than a hectare of willow. Unfortunately the UK has only 24 million hectares of land (and no, we’re not going to be growing willow on all of it). What are the rest of you going to do?

Still, it was a nice thought experiment.

The sorry state of science reporting


Like many independent thinkers, I’ve come to realise that reporting is rubbish. Science reporting in particular. Probably all reporting, but I like to think that I know a tiny bit about science, so I can spot the poor reporting more easily. Take this BBC article:

EU biofuel push ‘to ruin forests’

The headline is “EU biofuel push ‘to ruin forests'”. Then we read “Oil firms have warned that European Union plans on biofuels could wreck the world’s rainforests.”

So the news article is really an “anti bio-fuel” piece written by Big Oil. Big Oil is down on bio-fuel because you can grow it instead of drilling for it. Big Oil likes LPG and hydrogen because you can make those from crude. Imagine if cars ran on straight vegetable oil, you could grow it in your back yard! You can see why Big Oil might be a bit scared by that. Of course I don’t mean to say that Big Oil literally wrote the piece, but I mean that Big Oil hired a Respectable PR Company to write a Press Release which they put on the BBC editor’s desk and then passed to a sub who changed a couple of adjectives, rang a Rent-a-Quote and slapped it on the website. That seems to be how news is done these days.

Is this was a proper news article then I would expect to see a few sources. Who are these “oil firms”, as in “oil firms have warned …”? We just don’t know. You see how this is used to lend an air of credibility to the piece without actually having information that can be independently verified? Later on “one government official told the BBC: ‘The policy is running ahead of the science … ‘”. A government official? With a name? From what department? In what capacity did he tell the BBC this? Pure flak. Again, no verifiable information.

You can always tell where a sub has been. Consider this paragraph: “Experts agree it makes sense to maximise wood waste and to grow energy crops on land that is marginally productive for food.” The nameless experts of course provide filler without leaving a verifiable trail. But what does “maximise wood waste” mean? Perhaps before the sub came along it said “maximise biofuel production from wood waste” or something that actually made sense. Who knows. (Aside: wouldn’t it be better to sequester the carbon in wood waste and simply bury it?)

Again faceless experts are called in: “Many biologists warn there is simply not enough land on the planet … “.

Next up is an explanation that we’re supposed to take as given: “Already President Bush’s highly-subsidised drive to get fuel from the Prairies has triggered food riots in Mexico because it has pushed up the price of corn.” There’s no reference to any research or paper (or even a rent-a-quote) that claims that the riots were caused by the farming subsidies. No critical eye has been applied, just a bland “reprint whatever the press release says” approach. Are there any other possible causes? Is it possible that the riots were caused by trade agreements between Mexico and the USA? Or that the Mexican people are using this issue to protest at their government? There’s simply no investigation of alternative explanations. Big Oil says bio-fuel is bad because it causes riots, so that’s what goes to press.

Towards the end of the article we get to some quantitative blindfolding: We see that the UK government wants to produce 20% of electricity from renewable resources, but that the EU wants 20% of all energy to come from renewables. The article points out that since electricity accounts for about a quarter of all energy then that’s four times as much energy from renewables (than the UK government had in mind). Close, but no banana. What about approaches that involve producing less energy overall? If we produce less energy overall then that’s less renewable energy also. A sound article would at least mention this possibility including strategies of more energy efficient housing, more energy efficient cars, mass transport policies, aviation tax, and so on. In this BBC article? Simply not on the agenda. Of course the proportion of renewable energy is still four times higher (in the EU position versus the UK position), but the total need not be. (Aside: it’s totally bogus to set a target as a proportion, but this article isn’t about that debate)

The BBC are not a bad organisation. These days they’re just doing what everyone else is doing. Repeating without thinking. This article again is not a particularly bad article, I’ve certainly seen worse; it just happened to be the one that tipped me over into writing a blog post about bad science reporting. There are lots of example to choose from.

When you see a news article about something that you know about, how often is the article on the mark? Do you suppose that news articles about other things, things you don’t know so much about, are more accurate than those about which you know something?