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…


Sentences of note

Things I read / heard this week:


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.

Source: Bjorn Lomborg


“If I was Saddam Hussein and I really wanted to make a virulent flu virus, I would take a recently drawn flu virus, I would passage it through groups of 20 prisoners, I’d take the virus from the ones who were dying, and I would passage it through more. Anyone could do this. You just have to be unscrupulous enough.”

Source: Peter Doherty


People pay more attention to the number killed in a natural disaster than to the number of survivors when deciding how much money to donate (estimated at $9,300 per person killed). The number of people affected in the disasters, on the other hand, appeared to have no influence on the amount donated to relief effort

Source: Journal of the Association for Psychological Sciences

Bronze [at my] age

I’ve started running again and discovered the weekly 5km park runs organised across the UK.

Yesterday’s 5km run at hilly Hampstead Heath was better than expected:

Hampstead Heath Park Run Results

My first thought was, “wow, 3rd, and at my age!.” But inspecting the table it’s quickly clear that I’m not relatively old compared to the other top finishers.

It was the second highest attended race in this location’s 3-yr history (183 finishers) so plenty of data to play with which I put into Excel…

In terms of straightforward averages by ages, or median times, I could see no patterns.

Focusing instead on we ‘elite’ runners, ahem:

Hampstead Heath Park Run Male Finishers Average Times

Considering the top 3 runners in each age group, it does seem that mid 30s is the sweet spot for this kind of distance (for fit non-professionals, at least). The effect is even more pronounced upon removing potential outliers and considering the times for the 3 runners finishing in 4th to 6th place.

Investigating a little on the interwebs, this seems to be a real relationship. For example, data regarding aging and endurance performance for 10ks shows this:

Anyway, hats off to Jason Merron who was running around with a baby-filled buggy and still finished in the top half. I don’t know what the adjustment factor is for that…

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.