There are many things in the world around us that we don't understand or would like to predict. Scientists face uncertainty everyday and they design experiments to test their theories. As they progress with their research, they aim to decrease the uncertainty and increase their confidence in the results.

Curriculum links

Data, evidence, theories and explanations 1a. how scientific data can be collected and analysed
1b. how interpretation of data, using creative thought, provides evidence to test ideas and develop theories
1c. how explanations of many phenomena can be developed using scientific theories, models and ideas
1d. that there are some questions that science cannot currently answer, and some that science cannot address.
Applications and implications of science 4b. to consider how and why decisions about science and technology are made, including those that raise ethical issues, and about the social, economic and environmental effects of such decisions
4c. how uncertainties in scientific knowledge and scientific ideas change over time and about the role of the scientific community in validating these changes.


Scottish Curriculum for Excellence

Science general - experiences and outcomes express opinions and make decisions on social, moral, ethical, economic and environmental issues based upon sound understanding
develop as a scientifically-literate citizen with a lifelong interest in the sciences
SCN 4-20a. Topical Science: I have researched new developments in science and can explain how their current or future applications might impact on modern life
SCN 4-20b. Having selected scientific themes of topical interest, I can critically analyse the issues, and use relevant information to develop an informed argument
Environmental Science National 4 & 5 Potentially relevant to modules: Sustainability (environmental, economic and social impacts, and identifying possible solutions)
Science National 4 Potentially relevant to modules: Fragile Earth (resources and conflicts, benefits and issues and possible solutions, how science is involved in the cause, effect and resolution of environmental issues), Human Health (scientific analysis of health claims and consider moral and ethical issues), Science at Work (risk and safety)




What do people mean by ‘uncertainty’ in science?

What do people mean by 'uncertainty' in science?

lorenz systemThere are many things in the world around us that we don't understand or would like to predict. Of course no-one can say for certain what will happen in the future, but if we can make good predictions, for example when and where an earthquake might happen, then people's lives might be saved.

Image: Diagram of a Lorenz system, illustrating unpredictability in modelling weather.

Doctors need to know how a cancer patient might respond to a dosage of a drug. Scientists can use tests to trial a drug to predict what effects it will have on a patient. However people have different characteristics - they are different sizes, they have different genes - so one patient may respond differently to the same dosage of drug compared to another patient.

In science, models are often used to try and predict what might happen in the future. A model is something used when it is impossible or impractical (for example, too expensive) to use a real system to make measurements. They can be set up in many different ways, such as a practical experiment or as a computer simulation. Scientists study real measurements that have been taken in the past and use these to set up their model. They make assumptions about things that might happen and then test them using their model. For example, a researcher might want to know the effects of using wind generated electricity on the national grid. It would not be wise to really test this out on the nation's electricity supply in case something went wrong. So a model can be built that behaves in a similar way to the national grid. The researchers can test different ways of adding their model wind farm onto the grid and measure what happens.

In other areas such as climate change, scientists use computer models to try and predict what the climate might be like in the future. Scientists can input information about a number of different things like current measurements of greenhouse gases, the current population of the world etc.

These different characteristics that can be used to set up the model are called parameters. The parameters can be altered to give different outcomes based on different scenarios. For example the scientist could look at what might happen if the amount of carbon dioxide in the atmosphere doubled.

Professor David Spiegelhalter researches maths and statistics at the University of Cambridge. He specialises in looking at how maths is linked to the uncertainty of people's lives and our society as a whole.  In this video, he explains what uncertainty is and talks about different models used by scientists.  The video was made at a meeting about uncertainty where scientists from lots of different backgrounds got together to talk about how uncertainty is relevant to all fields of science (biology, chemistry, physics and everything in between). He finishes by saying how important it is for policy makers to understand uncertainty and how predictions are made.

Policy makers are the people who advise the government. The policy makers advising the government about climate change need to understand how the different predictions have been developed. Some models may not include all measurements - Professor Spiegelhalter mentions one that doesn't include methane levels. It is important that the policy makers understand this so they can work out why there are different predictions about what might happen to the climate in the future and give the government good advice.


Why is it important?

flood_300Scientists face uncertainty everyday and they design experiments to test their theories. As they progress with their research, they aim to decrease the uncertainty and increase their confidence in the results.

It is not just scientists that have to make decisions based on uncertainty. Other organisations such as governments, banks and insurance companies will make changes to their policies based on probabilities and predictions. For example after a major disaster like a flood, insurance companies will make their insurance for flood damage more expensive. They would do this because they predict that if a house has been damaged by a flood, it is more likely to be flooded again in the future.

Governments can have a big influence on people's behaviour and their daily lives by increasing taxes on certain behaviours (eg driving cars) or giving money to organisations for other behaviours (eg recycling). These policies have been based on advice and predictions.

Everyone makes predictions everyday, and they're almost always uncertain. A neighbour might have had a dream about lottery numbers and changed their behaviour by buying a lottery ticket that day, but a prediction like this cannot be tested scientifically.

It is vital that decision making bodies like the government use predictions that have been tested and are based on real evidence when they make decisions that change people's lives and the way they behave. Although predictions are almost never 100% accurate they can reduce the amount of uncertainty and help people to make informed decisions.