Survivorship bias is a term used to describe a type of selection bias. It occurs when a set of data for analysis is skewed by excluding certain data points due to the selection process. When the surviving data are examined as the only relevant examples, they produce inaccurate results because relevant data have been excluded.
Survivorship bias exampleA research study carried out on trauma patients admitted to a hospital emergency unit aimed to discover which procedures carried the best success rate. However, the researchers were only able to consider those patients who are well enough to give consent.
This means that the study does not include the most sick patients or those who do not survive, and the results are unrepresentative.
Primacy bias describes how it is usually easier to recall information we heard earlier in an interaction. So, if we read a long list of items, we are more likely to remember the first few items in the list than the ones we read later.
Primacy effect exampleAt a conference, you meet a considerable number of people who are new to you in the first hour or so. Later in the day, as you encounter these new people again, you realize that you remember the names and some details of only the first few people you met.This is primacy effect at work.
Anchoring bias is a type of cognitive bias that affects the way we perceive information and consequently the decisions we make. It describes our tendency to rely too much on the first piece of information we receive on a topic, irrespective of how reliable that information might be. As a consequence, anchoring bias can lead to poor decision-making.
Anchoring bias exampleYou visit a used car showroom with a view to purchasing a new vehicle. The dealer shows you around a number of cars that you realize are far beyond your price range, and you start to think that you can’t afford to change.
Next, the dealer shows you some other, much cheaper cars that are within your budget. Compared with the earlier, expensive models, these seem like good value. This impression is misleading, as in reality, they are all overpriced. But because the first cars have fixed a price in your mind, they seem like a good buy.
Self-serving bias describes the human tendency to take credit for our successes and to blame others or circumstances for our failures. In other words, our success is down to our personal traits and character, and our failure is due to external factors beyond our control.
It is difficult to learn from our mistakes if we suffer from self-serving bias because it stops our reflecting on what we have done and analyzing why it went well (or went wrong). It is common to encounter self-serving bias when people are explaining underperformance in sports, driving, or work.
Self-serving bias exampleWhen Steve leaves home in plenty of time to get to work, he congratulates himself on being organized and punctual. On the occasions he doesn’t leave enough time, he blames traffic, roadwork, and other drivers for his late arrival rather than his leaving late.
Published on
September 9, 2024
by
Trevor Marshall, MSc
Revised on
September 30, 2024
The availability heuristic describes our tendency to evaluate the likelihood of something happening according to how easily we can recall a similar occurrence. It can be seen as a mental shortcut we use to help us process information and respond to the many stimuli around us. An easily remembered event can cause us to mistakenly judge a similar event as more likely to happen.
Availability heuristic exampleMany people will reach for their phones when the flight they are on lands and text their loved ones that they have landed safely. In almost every country in the world, though, they are about to start the most dangerous part of the journey if they plan to travel by car.
Statistically, road transport is much more dangerous than air travel. But an airplane crash is given widespread news coverage, and the availability heuristic means that we feel it is the dangerous part of the journey. If there has been a recent disaster, this effect is even more pronounced.
The availability heuristic doesn’t just affect our perception of our safety when traveling but can have serious consequences for research and risk assessment. Understanding research bias can help us avoid it having a negative effect on research and trials.
A self-fulfilling prophecy describes a set of circumstances where a person’s belief about a future situation contributes to that belief coming true. It is more likely to be a negative belief or outcome. The explanation for the phenomenon is that our expectations unconsciously affect our behavior.
Self-fulfilling prophecy exampleYou are a keen amateur photographer, and your brother has asked you to photograph his wedding. You can’t really say no, but you don’t think you are good enough. As a consequence, you are nervous on the day, fumbling with the camera and equipment, and making the bridal party and guests nervous.
As a result, the photos are awkward and don’t come up to the standard you would like. Your beliefs about your abilities have caused you to underperform, and what you feared would come true, has.
A self-fulfilling prophecy is not necessarily a negative thing, and it can be positive. Self-fulfilling prophecies can be found in all manner of contexts, such as business, healthcare, or education.
Published on
July 12, 2024
by
Tom Challenger, BA
Revised on
October 10, 2024
The representativeness heuristic is a mental shortcut we use to decide the probability of something based on how typical we think it is. We assign this thing to a category and decide how similar we think it is to an “average” representative of that category.
Representativeness heuristic exampleYou are on the train with a friend, and a woman sits down opposite you.
She is dressed in colorful, flamboyant clothes and is reading the arts section of The New York Times.
When she gets out at the next stop, your friend says, “Do you think she was a famous artist?”
You reply, “Well, she definitely wasn’t a lawyer!”
Although there is a much greater proportion of lawyers in the population than artists, you think that the woman is more likely to be an artist because her appearance and choice of reading material match your perception of a typical artist.
The representativeness heuristic allows us to make quick and efficient decisions, but it can cause us to arrive at false conclusions and disregard relevant information.
The placebo effect refers to a phenomenon whereby patients experience an improvement in their physical ailment after taking a non-treatment, called a placebo.
The treatment contains no active ingredients, meaning that any improvement experienced by the patient is caused by their expectation or belief that the “treatment” is doing them some good.
Placebo effect exampleAs a life-long sufferer from back pain, you are invited to take part in a double-blind trial of a new treatment. It is a preventative treatment, and you take one pill three times per day, as instructed, and record your pain levels in a journal. At the end of the month-long trial, your journal shows that the medication appears to be having a positive effect, as there is a clear improvement in the levels of chronic pain.
When you report your findings to the researchers, you (and they) discover that your treatment was, in fact, nothing more than a sugar pill rather than the new drug. The improvement you perceived was due to the placebo effect.
In double-blind medical trials, where the experimental design includes both control and treatment groups, the placebo effect is often seen in the control group.
Recency bias is the tendency of recent events to receive more weight in our thinking when we make decisions about a future course of action. Because they are recent, some events loom large in our consciousness as we consider likely future outcomes.
Recency bias exampleRecency bias can be seen in people’s attitude to flying. Although airplanes remain one of the safest forms of transport, news reports of an air disaster can affect people’s willingness to fly, or how anxious they are when flying.
The recency of the event makes flying seem less safe.
Our brains are more likely to recall recent events than past ones, and these can override our ability to analyze clearly.
Published on
July 2, 2024
by
Tom Challenger, BA
Revised on
September 20, 2024
Hindsight bias is our tendency to overestimate how predictable we thought an event was after it has happened. This can lead to overconfidence about our powers of judgment and cause us to make risky decisions or unfairly criticize the actions of others.
Hindsight bias exampleMartin is a soccer fan and goes to watch his favorite team play on the weekend.
The coach of the team has decided to include a young player in the starting lineup.
Martin discusses this decision with his friend before the match. They agree that it is a bit risky because the young player is inexperienced, but it is good that he will be replacing a player who did not play well in the last match.
Martin’s team loses the match. At work on Monday, he discusses the result with one of his colleagues. Martin says that he knew his team would lose because the young player was too inexperienced.
Hindsight bias has made Martin think that he was certain that his team would lose. But in truth, he did not predict this with confidence.
Hindsight bias is also known as the “knew-it-all-along phenomenon.” It can lead us to wrongly believe that an outcome, such as a sports score, election result, or medical error, was more certain than it actually was.
