Back-of-the-envelop calculations can be a springboard for interesting questions about a topic. It can be used to dissect government announcements or the opinions of experts. A calculation on one of the critical elements of life - food - unearthed a lack of government action.
As the name suggest a back-of-the-envelop calculation is just that: a calculation done on a piece of paper the size of an envelop. Taking some key numbers for a topic, a quick calculation can be done to to assess whether what is being claimed makes sense. If it doesn’t then more details can be sought or the assumptions made to do the calculation can be checked. Back-of-the-envelope calculations are used regularly by engineers and scientists to quickly check whether their ideas are doable. But they can be seen being used on TV. One prominent example where the use of the back-of-the-envelop calculations is Sir John Harvey-Jones in his series The TroubleShooter, where he visited businesses that were in financial trouble. As he went around the company talking to various people he would jot down numbers in a small book then using the resulting calculations he would give advice on the best way forward. Another example is on The Dragons Den where the dragons are seen scribbling down numbers during a pitch for investment then based on their calculations may offer a deal for a stake in the business.
Recently I was reading Yanis Varoufakis’ interesting book Talking to My Daughter About the Economy when I came across the term “surplus” in connection with agriculture. The book went onto describe it it as “… simply meant any produce of the land that was left over after we had fed ourselves and replaced the seeds used to grow it in the first place.” and goes on “ … the production of agricultural surplus gave birth to the following marvels that changed humanity for ever: writing, debt, money, states, bureaucracy, armies, clergy, technology and even the first form of biochemical war.” Quite a claim.
The idea of a surplus supporting life raised questions about how many people in agriculture support the rest of the country. Searching for a few numbers on the web I found that there are approximately 466,000 people working in the agriculture industry. The population in the UK is about 67.5 mn. The back-of-the-envelope calculation shows that it take one person to feed approximately 140. Is that ratio good or bad? Checking other countries such as Germany where the ratio is approximately the same as the UK. In Spain it is approximately 1 person feeding 58. The difference between Spain and the UK is probably down to levels of mechanisation. The thought that struck me while doing this calculation is that we depend on very few people to produce our food. Compared to other industries such as Management Consultancy where there are roughly the same amount of people as in agriculture yet given the UKs lack of productivity questions have to be asked about its effectiveness.
The next question that comes to mind was about the level of agricultural productivity. The UK is about 60% self sufficient in the growing of its own food. Whereas Germany food self-sufficiency is 80%. The only European country to be self-sufficient is France. Given that the global supply chains are being disrupted by climate change and geopolitics it would be prudent for the UK to increase its self sufficiency in food to say 80% ( we would still need to import food that we can’t grow such as tea and coffee etc. ).
Therefore, this increase in self sufficiency would require a 33% increase in either mechanisation or automation or employing about 100,000 more people in agriculture. The UK Goverment’s Food Strategy recognises that there needs to be an increase in food self-sufficiency but there are no clear plans to achieve that aim. For example there is lots of discussion about the increased use of robotics but looking at the current developments from companies such the Small Robot Company’s, where they are developing the exciting concept of per plant farming, it is tens of years away from main stream agriculture. There is very little discussion about how more people could be attracted into agriculture. Food production is a critical activity in our lives and the UK government must be more proactive in securing its future rather than leaving it to market forces which is undermining its sustainability.
Back-of-the-envelope calculation bypass a lot of complexity but it is a quick way to start a series of questions that digs down into the difference between what is being claimed and what is being done. Anybody who can do simple arithmetic can carry them out and in the case of government policy back-of-the-envelop calculations can be used to ask questions that can hold them to account.