When the wind blows

I looked today at investing into a company setting up a small wind turbine. I’ll keep the numbers round for confidentiality reasons.

£700k start-up costs, with a 75% chance in any year of generating enough energy to sell at 5p / kwhr to the grid for £30k.

10% of revenues go to the site’s landlord, and a flat £15k per year to the manufacturer for a full maintenance contract.

This is clearly not viable. Fortunately there is an additional subsidy of 18p / kwhr (rising annually) due to the Government’s Feed-in-Tariff.

Nothing about this site will get cheaper over time. Assuming a life span of 25 yrs and a 10% discount rate, the turbine and other start-up costs would have to drop from £700k to £100k for future such ventures to start to look interesting sans subsidy.

In the UK the total subsidies needed for all such schemes are added up, and then divided out amongst all consumers’ bills, so it’s not clear to the general public just how much more expensive (it appears 4x as much) some alternative energy sources are costing.

Future Governments change their minds about policies. And for that reason, I’m out.

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Don’t mention the solar panels

On a flight this morning I began to think that the Bjorn Lomborg quote I heard yesterday couldn’t be plausible:

Germany once prided itself on being the “photovoltaic world champion”, doling out generous subsidies – totaling more than $130 billion to citizens to invest in solar energy…by the end of the century, this will have postponed climate change temperature increases by 23 hours.

So I tried a quick back of the envelope calculation:

German population = 70m

Global population = 7bn

Ratio = 1/100

Number of years solar panels last for = 20

Years over which CO2 emissions have and will accumulate before the bad temperature rise (say 2100 – 1900) = 200

Ratio = 1/10

Reduction in CO2 emissions of Germany = 1/100 (the article gives a less than 1% current total supply by solar)

Germany’s level of emissions during these 20 periods relative to global average over 200 years = x2

Total portion of CO2 from global total that will be avoided =(1/100) x (1/10) x (1/100) x 2 = 2/100,000

Number of days over which CO2 emissions occur = 365 * 200 = 70,000ish

Over 1m Germans have solar panels installed. Number of days of CO2 emissions avoided from these, i.e., how much extra time is bought before a catastrophic temperature increase  = 70,000 x 2 / 100,000 = 1.4 days

Wow. Well done. I definitely feel less bad about my flight now. Not that I was.

I came across Without Hot Air several years ago and found it to be very credible – same approach, back of the envelope physics…I seem to have just complimented myself on being very credible. I’d best stop myself here. It’s not impossible I’ve missed something obvious out of the above…

No claims bonus

I saw this ad on the tube:

Pregnacare advertisement

And was struck by the types of claims made:

  • Most trusted by mums
  • Brand midwives recommend most
  • No 1 pregnancy supplement brand
  • Award for innovation in vitamins research

None of these is a scientific claim relating to an actual improved pregnancy/birth outcome. Indeed, Vitabiotics have had several of their adverts banned by the ASA for making unsubstantiated medical claims. See here, here, and here.

This page on their website has graphics corresponding to these claims, with links to the sources, as well as to the British Journal of Nutrition which published a paper that is the source of Pregnacare’s most scientific-sounding claim that:

…landmark in research was achieved … showing that Pregnacare tablets reduced the number of small-for-gestational-age (SGA) infants (low birth weight for time of birth) relative to the placebo.

The study of over 400 newly pregnant women … was the first ever reporting of clinical findings … showing that supplementing with a specific multivitamin supplement helps reduce the number of SGA infants born.

Except it’s not an actual working link, just a graphic which has the same visual appearance of the real links during a mouseover. I tracked down the paper because I had nothing better to do on a Monday night.

The researchers tried to recruit 2,385 socially and economically deprived mostly immigrant pregnant women in Hackney, East London. Only 402 subsequently participated (for example >10% of the sample were unable to speak English and therefore could not give consent). The 402 were given Pregnacare or a placebo tablet, but most dropped out leaving only 150 mothers who took the tablets regularly. This is the outcome:

Pregnacare Clinical Result

The intention-to-treat analysis shows no difference in SGA numbers. There is in those fully compliant, and although that is in favour of Pregnacare, those receiving treatment were more likely to have a low birth weight child (even after a longer gestation period) – which is a more serious issue. (See this v this).

As far as I can see, after 1 hour of my life that I’m not getting back, giving vitamins to a multi-ethnic group of low-income pregnant women, of which 72% had a vitamin D deficiency to begin with, “may,” in the smallest print showing on the advert, “benefit those with nutritionally inadequate diets”. No shit. But if you’re short of time, pregnant, and read “Pregnacare” you may well take the cognitive shortcut that these tablets will help you take good care during your pregnancy.

Over the moon

Here’s how the moon looks from earth:

20130630-023207.jpg

And here’s how Jupiter would appear if it was the same distance away:

20130630-023318.jpg

Source.

Genes

Today I went to a ‘bite-sized lunchtime lecture’ at UCL, and courtesy of Dr Sara Hillman learnt that a low birth weight child was a predictor of future diabetes in the father, and that in turn having a father who smoked was a predictor of the baby being born with a low birth weight.

And then across the road at the Wellcome Trust had a look at a set of books mapping all 23 chromosomes containing the complete human DNA sequence:

 

There are 3 billion letters in the books, and if you compared your own DNA to the sample in the book you’d find only a few million differences

Do rich people steal children’s sweets?

This article,  “Interesting: being rich doesn’t make you good! Now, there’s a surprise!“, is a good example of how stories propagate around the internet. Its author, Richard Murphy, described as “the UK’s #1 economics blogger,” [edit: see one of the comments for some info on this] reproduces an infographic he’s found and states

“…it also looks properly sourced, so I thought it worth sharing.”

Here’s part of it:

You can see the full infographic reproduced in the article, with many more similar claims.

Let’s take two of the claims, paraphrased in the context they’re presented:

  1. Rich people steal more sweets from children
  2. Rich people are more likely to cheat others out of their money at games.

 

I checked the link given at the bottom of the infographic: http://www.livescience.com/18683-rich-people-lie-cheat-study.html. This article doesn’t name the  paper, nor does it even give the sizes of the studies.

So the source of this “properly sourced” item is itself not even sourced (I tracked down the paper, it’s Higher social class predicts increased unethical behavior, PNAS (2012).)

 

For claim #1, 129 students were given a picture of a ladder with 10 rungs and told, “Think of the ladder as representing where people stand in the United States … Where would you place yourself on this ladder relative to these people at the very top? Imagine yourself in a getting acquainted interaction with one of the people you just thought about from the top/bottom of the ladder and write a brief description about how you think this interaction would go.”

Shortly thereafter they were asked to take a jar of 40 sweets to a child-specific laboratory, and were invited to help themselves to a few if they wanted. On average the 129 students took 1 sweet, with a S.D. of 1.

No more numbers than this are given, but I would say the evidence for claim #1 is something like: 60 students who thought about talking to poor people mostly accepted a couple of sweets when offered them, and 60 students who were thinking about rich people mostly declined. Right.

 

Claim #2 is based on 195 people responding to a Craigslist advert to take part in an online study after which they would be entered into a draw to win a $50 voucher for an online retailer.

They were divided into rich or poor based on answers to a survey about their background (sorry, but how rich exactly were the richest people in this group to need to take part in a study hoping to win $50?) Participants were presented with a computer program which randomly rolled five dice, the entrant with the highest score winning the $50 gift certificate. Test-takers had to report the scores themselves, but didn’t know the program was rigged to always generate a score of 12. A full 85% of people answered honestly, but out of the 31 participants reporting getting more than 12, there were a few more “richer” people than poorer people.

I’d restate claim #2 to suggest that poor people doing online surveys are probably poor because i) they’re not being productive with their time, and ii) they might help themselves by doing things such as typing the biggest number possible into a box in order to maximise their chances of making themselves $50 better off.

 

Perhaps the conclusion here is that people are inclined to believe what they want to believe, and are less questioning of claims consistent with that. The guy writing that this looks “properly sourced” was voted the seventh most influential left wing thinker in 2010/11, and as such likely has a world view on rich-v-poor with which the infographic resonates. Indeed, many web and print news outlets ran with stories based on this study, using headlines such as, e.g., Rich people more likely to take lollies from children, presumably because it’s a headline that would catch the attention of many of us and appeal to our biases.

 

Other dodgy stats:

BBC and selection bias

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God does not play baseball

A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?

The same question was used in a survey on belief in god:

“Some say we believe in God because our intuitions about how and why things happen lead us to see a divine purpose behind ordinary events that don’t have obvious human causes,” study researcher Amitai Shenhav of Harvard University said in a statement. “This led us to ask whether the strength of an individual’s beliefs is influenced by how much they trust their natural intuitions versus stopping to reflect on those first instincts.”

Shenhav and his colleagues investigated that question in a series of studies. In the first, 882 American adults answered online surveys about their belief in God. Next, the participants took a three-question math test with questions such as, “A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?”

The intuitive answer to that question is 10 cents, since most people’s first impulse is to knock $1 off the total. But people who use “reflective” reasoning to question their first impulse are more likely to get the correct answer: 5 cents.

Sure enough, people who went with their intuition on the math test were found to be one-and-a-half times more likely to believe in God than those who got all the answers right. The results held even when taking factors such as education and income into account.

More here