Monday, February 27, 2012

Science Literacy and Guesstimating Skills

This is a weekly post by Nidhal Guessoum (see his earlier posts here). Nidhal is an astrophysicist and Professor of Physics at American University of Sharjah and is the author of Islam's Quantum Question: Reconciling Muslim Tradition and Modern Science.

The past two Fridays, GulfNews published two columns of mine that try to highlight the importance of science literacy and the rarely appreciated, much less taught, art/science of “guesstimating” (producing educated guesses or “back-of-the-envelope” estimates for questions without or before having to perform the full calculation).
Here are excerpts from each article, starting with the science literacy one:
On the first day of my Astronomy course, I give students a “pre-assessment” quiz for me (and for them) to get a general idea of the knowledge – and misconceptions – they bring in. Questions include: how old are the universe, the sun, and the earth; who was Copernicus; and what is the difference between a planet and a star… Few students are able to answer these questions correctly.

What I don’t tell my students is that a famous documentary once asked Harvard students on the day of their graduation why it is hotter in the summer than in the winter (in the northern hemisphere), and fewer than ten percent of them answered correctly. Similarly, at George Mason University, half of the seniors who were surveyed could not state the difference between an atom and a molecule. Such ignorance is much more widespread in the general public, as half of the (surveyed) American public does not know how long it takes the earth to orbit around the sun, and one in five thinks the sun goes around the earth. In recent studies, only about 7 % of American adults were judged to be “scientifically literate”…

Science literacy is the general understanding of scientific ideas (facts, terms, theories); it allows a reasonably educated person to digest scientific information that is received from various media; it also allows one to follow the discussion on a science-related topic (say stem cell research) and come to an informed conclusion. It is important to stress that such literacy is broad and does not depend on one’s scientific training. Indeed, studies (in the west) have shown that many scientists who possess high but narrow expertise in their fields do not have enough general and broad knowledge in other areas. (How many non-biologists know the difference between genes and chromosomes?)
Why is this type of literacy important?
The situation in the United States is quite instructive, because it has been studied for many years and in different population samples, and experts have been able to draw some useful conclusions. They have found that while the general public in the US is not very scientifically literate (not at international standards), Americans who have gone to college and majored in any field end up acquiring significant science literacy. This is because contrary to most other higher education systems, American universities require all students (even those majoring in arts or humanities) to take and pass 1 to 3 science courses.

Another important remark is the realization that Americans go to museums, zoos, and aquariums quite frequently; indeed, 30 % of US residents visit a museum in a given year, compared to 16 % of Europeans and 14 % of the Japanese; 58 % of Americans visit a zoo or an aquarium each year, compared to 9 % of Europeans and 32 % of the Japanese.
Read the whole (800 words) article here.
And here are a few paragraphs from the piece on guesstimating skills:
My students are often stunned to hear me ask them to estimate or even guess some answers. The expressions on their faces, and often the words from their lips, say it clearly: are you asking us to guess in a technical, scientific course at a respectable university? Yes, indeed, I not only ask my students to “educate-guess”, I try to show them the importance of this skill and how to learn it.

It was the Italian-American Nobel Prize winning physicist who made this skill popular when he posed to his (doctoral) students such questions as: how many piano tuners are there in Chicago; how far can a duck fly; and other such strange questions, which “obviously” had nothing to do with science or with education… Answering these kinds of questions, for which one could never obtain a precise result, became known as “guesstimating” or performing “back-of-the-envelope” calculations.

Why did Fermi want his students to be able to answer such questions? Why is this guessing/ estimating an important skill to acquire? I tell my students (most of whom are Engineering majors) that when they have an idea or a project they wish to propose to their supervisors, or if one of their staff members brings a proposal to them, that they better be able to quickly estimate the cost, the feasibility, the timescale needed, and the drawbacks in the idea under consideration. Moreover, if they want to convince their superiors of the need for some projects, they should be able to show simple and convincing numbers to the decision-makers.

For example, one should be able to estimate the amount of water lost in the undammed rivers of a given state, or the amount of time wasted by drivers or pedestrians or employees due to certain urban or architectural constructions, or the amount of energy that could be saved (and the attached costs) in placing solar panels on the roofs of a building. One simple and favorite question of mine is to ask students to estimate/calculate the amount of money they waste by skipping one class, knowing how much their parents have paid for their tuition in a given semester…

The tricky part is that for one to do a good estimate, one needs some facts/knowledge, some of which may not be available or easily accessible. And that is when the skill of “educated-guessing” comes in as an important tool. Conversely, when one is shown a result (say a student or an engineer brings me a calculation), one must be able to quickly check (by guesstimating) whether the result makes sense or not. This is where one combines some essential knowledge, some sharp mental skills, and some critical thinking. This is how the above components of education combine; this is what makes a smartly educated person in today’s era of quickly accessible facts.
Einstein once said “everything should be made as simple as possible, but not simpler”. By this he meant that one should be able to solve problems as simply (not as precisely) as possible, but simplicity must not sacrifice the above elements of: basic facts/knowledge, sharp logic/skills, and critical thinking. We need to integrate this more fully into our approach to education.

Read the whole thing here, including some such questions I proposed that the readers try to tackle…


Gary said...

Salaams Nidhal

Two examples of the importance of guesstimation come to mind. A work colleague of mine had to learn surveying as part of his work training. His teacher was a former WWII navy engineer who used to build things such as airstrips on new beach-heads in the Pacific. He impressed his students with his ability to swiftly solve surveying calculations. Of course the was using short cuts to get approximate results which were adequate for the task. There is nothing like trying to build an airfield under enemy fire to sharpen your ability to guesstimate.

The other story which comes to mind is a description I read of Enrico Fermi when they achieved the first nuclear chain reaction during the Manhattan Project. He was taking all the various readings from the process and furiously doing calculations using his slide rule. He had probably already thought the problem out in advance but I suspect in the end the presence of a live atomic bomb in the room probably encouraged him to do some very quick guesstimates.

Another skill which you touched on is the ability to rethink a problem. I often did this when confronted with consultants reports which were just too incredible even for consultants. On one occasion I discovered an incorrect briefing had been given resulting in a 1000% error in essential engineering calculations. On another a team of consultants who were clearly operating out of their area of expertise produced an outrageously high estimate for a project budget. A quick back of the envelope calculation, (actually it was a post it note)using the consultants own figures convinced management that by doing things my way instead of following the consultant's gold-plated recommendations I could bring things back to budget. My final estimate was 75% less than the consultants and within 2% of the actual cost at completion. It is amazing how quickly you can think when your job is about to disappear because it will cost too much to build the laboratory you need to work in.

Nidhal Guessoum said...

Thanks, Gary, for adding your own real examples of the usefulness of guesstimating skills and for underscoring the link to critical thinking. Indeed, the ability to do quick estimates, even just at the order-of-magnitude level often allows one to shoot down claims or to make sure that a more "precise" (i.e. technical, based on equations and whatnot) is not just totally erroneous. This is also a hugely needed skill in cases of financing projects, as you point out, where it is so easy to go wrong, honestly or deliberately.