Nepedia
Back to Discover
Advanced Reader
🔢

Uncertainty

math Maturity 13-18 Next article →

Uncertainty describes a state of limited knowledge where information is imperfect or unknown. It occurs when we cannot exactly describe a specific goal, a set of options, or the possible future states of a system. This concept is essential for decision-making in many fields. It applies to predicting future events and to physical measurements that have already been taken. Uncertainty arises in environments that are complex, dynamic, or stochastic. It can also result from human ignorance or indolence.

Uncertainty
Uncertainty

Specialists in statistics and decision theory often distinguish uncertainty from risk. Risk exists when the future value of an outcome is unknown, but an estimated value can be calculated. In a risk scenario, some outcomes may result in an undesired effect or a significant loss. To measure risk, one uses a set of outcome probabilities paired with the valuations of those outcomes. This often includes loss functions over continuous variables. Some experts argue that because an expected value can be calculated for risk, it is not a true form of uncertainty.

There are further layers of complexity in how we quantify these concepts. Second-order uncertainty refers to the confidence one has regarding probability estimates. In economics and statistics, this is represented by probability density functions over first-order probabilities. There is also a distinction between risk and variability. Risk is quantified by a probability distribution based on the likelihood of a single future value, such as a roll of the dice. Variability is quantified by a distribution of frequencies from multiple instances of a quantity, such as a batting average derived from observed data.

In 1921, economist Frank Knight introduced a famous distinction known as Knightian uncertainty. He separated risk from uncertainty by looking at what can be measured. Knight argued that risk is theoretically insurable because it has a clearly defined expected probability distribution. However, true uncertainty is immeasurable and impossible to calculate. Because there are no clearly defined statistics for these situations, probabilities cannot be determined. Knight noted that entrepreneurs are often the ones who bear this uncertainty, which can create new opportunities in the field of entrepreneurship.

Modern thinkers have expanded these definitions even further. John Kay and Mervyn King popularized the term "radical uncertainty" in their 2020 book. They distinguish radical uncertainty from Knightian uncertainty based on whether it is resolvable. If uncertainty comes from a lack of knowledge that can be fixed through research, it is not radical. Radical uncertainty exists only when there are no means available to acquire the knowledge needed to resolve it.

Blank Fork
Blank Fork

Other forms of uncertainty involve how we interpret information. Vagueness occurs when an analyst cannot clearly differentiate between two classes, such as defining the line between "average height" and "tall." Ambiguity happens when the possible outcomes themselves have unclear meanings. For example, the phrase "He returns from the bank" is ambiguous because "bank" could mean a financial institution or the side of a river. Daniel Ellsberg is well known for his urn experiments, which helped illustrate how people avoid ambiguity differently than they avoid risk.

Uncertainty also plays a fundamental role in the physical sciences. In quantum mechanics, the Heisenberg uncertainty principle places limits on what an observer can know. It states that there are limits to knowing both the position and the velocity of a particle. Some scientists debate if this is simply due to a lack of information. Others suggest it may be an irreducible property of the universe, meaning there is no fact to be found. This connects uncertainty to the very fabric of physics and metrology.

In the field of measurement, known as metrology, scientists use specific procedures to handle uncertainty. The "Guide to the Expression of Uncertainty in Measurement" (GUM) provides a standard method. Measurement uncertainty generally consists of several components categorized as Type A or Type B. Type A components are evaluated using statistical methods. Type B components are evaluated by other means, such as assigning a probability distribution. By propagating these variances, scientists can calculate a combined measurement uncertainty to provide a margin of error.

673 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (2)
File:Blank Fork.png
Blank Fork.png
File:Uncertainty.svg
Uncertainty.svg
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.