In the complex world of decision-making and data analysis, there’s a subtle yet powerful cognitive error that often goes unnoticed: survivorship bias. This phenomenon can skew our perception of reality, leading to flawed conclusions and misguided strategies. Understanding survivorship bias is crucial for anyone looking to make informed decisions based on data and observations.
What is Survivorship Bias?
Survivorship bias is the logical error of concentrating on people or things that “survived” a selection process while overlooking those that did not, typically because of their lack of visibility. This bias can lead to overly optimistic beliefs because failures are ignored or underrepresented.
The term “survivorship bias” is often attributed to Abraham Wald, a Hungarian-American mathematician who made significant contributions to decision theory, geometry, and econometrics during World War II.
The Classic Example: World War II Bomber Planes
Perhaps the most famous illustration of survivorship bias comes from World War II. During the conflict, the American military was looking for ways to minimize aircraft losses to enemy fire. They examined returning planes, noting where they had taken the most damage, with the initial intention of adding armor to those areas.
However, a statistician named Abraham Wald pointed out a crucial flaw in this thinking. The military was only considering the planes that had survived their missions. The bullets holes they were seeing represented areas where a plane could take damage and still fly home.
Wald proposed that instead of reinforcing the areas with the most bullet holes, they should reinforce the areas that had no bullet holes. His reasoning? The planes that were shot in those areas weren’t returning at all. These were the vulnerable parts that, when hit, would bring down a plane.
This insight likely saved many lives and aircraft. It’s a perfect example of how survivorship bias can lead to dangerously wrong conclusions if we only consider the “survivors” in our analysis.
Survivorship Bias in Everyday Life
While the World War II example is dramatic, survivorship bias affects our thinking in many less obvious ways:
1. Business and Entrepreneurship
We often hear stories of successful entrepreneurs who dropped out of college to start their businesses. This can lead to the false conclusion that dropping out of college is a good path to business success. However, we don’t hear about the many more dropouts who failed in their ventures. The successful ones are simply more visible.
2. Investment and Finance
Mutual funds often close or merge poorly performing funds into more successful ones. This can make the overall performance of mutual funds appear better than it actually is, as the failed funds disappear from the data.
3. Health and Lifestyle
When we hear about a 95-year-old who attributes their longevity to a daily glass of whiskey, we’re tempted to believe in the health benefits of alcohol. But we don’t hear from all the people who had the same habit and didn’t live as long.
4. Career Advice
Successful people often give advice based on their personal experiences. While this can be valuable, it may not account for the many others who followed similar paths but didn’t achieve the same success.
The Dangers of Survivorship Bias
Survivorship bias can lead to several negative outcomes:
- False Optimism: By focusing only on successes, we may underestimate the risks or difficulties involved in a particular endeavor.
- Misallocation of Resources: Like in the World War II example, we might invest time and resources in the wrong areas if we don’t consider the full picture.
- Flawed Decision-Making: Basing decisions on incomplete data can lead to poor choices in business, investing, and personal life.
- Unrealistic Expectations: Survivorship bias can create unrealistic expectations of success, leading to disappointment and frustration.
How to Overcome Survivorship Bias
Recognizing and overcoming survivorship bias requires conscious effort and critical thinking. Here are some strategies:
1. Look for the Failures
Actively seek out information about failures or unsuccessful attempts in any field you’re studying. This can provide valuable insights and a more balanced view.
2. Question the Data
When presented with data or statistics, always ask about the sample. What’s included, and more importantly, what might be missing?
3. Consider Base Rates
Understanding the overall probability of success in a given endeavor can help contextualize individual success stories.
4. Seek Diverse Perspectives
Don’t rely on a single source of information. Seek out diverse viewpoints and experiences to get a more comprehensive understanding.
5. Be Wary of Simple Explanations
Success and failure are often the results of complex factors. Be skeptical of overly simplistic explanations for success.
Survivorship Bias in Different Fields
Science and Research
In scientific research, there’s a tendency to publish positive results more often than negative ones. This “publication bias” can skew our understanding of certain phenomena or the effectiveness of treatments. Researchers and readers need to be aware of this bias and seek out unpublished or negative results to get a full picture.
Sports
In sports, we often hear about the intense training regimens or unique habits of successful athletes. However, we rarely hear about athletes who followed similar practices but didn’t achieve the same level of success. This can lead to the adoption of training methods or techniques that may not be universally effective.
Education
Educational policies are sometimes based on studying high-performing schools or students. However, this approach may miss crucial factors that are holding back lower-performing schools or students. A more comprehensive approach would involve studying both successful and struggling institutions to identify true best practices.
Technology and Startups
The tech world is full of stories about garage startups that turned into billion-dollar companies. While these stories are inspiring, they can create a skewed perception of the startup landscape. For every successful startup, there are countless others that fail, often due to factors beyond the founders’ control.
Historical Examples of Survivorship Bias
Beyond the famous World War II bomber example, history provides us with several other instances where survivorship bias played a significant role:
The “Healthy Soldier” Effect
During the Crimean War in the 1850s, Florence Nightingale observed that soldiers in the field hospitals had a higher mortality rate than those in the barracks. Initially, this led to concerns about the quality of care in field hospitals. However, further analysis revealed that soldiers in the barracks included many who were too sick to be sent to the front lines. The seemingly higher survival rate in the barracks was actually due to survivorship bias – the sickest soldiers never made it to the field hospitals in the first place.
Ancient Roman Buildings
We often marvel at the durability of ancient Roman buildings that have survived for thousands of years. However, this admiration may be colored by survivorship bias. We don’t see the many buildings that collapsed or were torn down over the centuries. The buildings that survive may not be representative of typical Roman construction, but rather exceptional examples that have withstood the test of time.
Survivorship Bias in the Digital Age
In our modern, data-driven world, survivorship bias takes on new forms and presents new challenges:
Social Media Success Stories
Social media platforms are filled with success stories of influencers, entrepreneurs, and self-made millionaires. These stories can create a false impression of how easy it is to achieve such success. What we don’t see are the countless individuals who attempted similar paths but didn’t achieve the same results.
App Store Rankings
When browsing app stores, we typically see the most successful and popular apps. This can give app developers an unrealistic expectation of success. The vast majority of apps struggle to gain traction and visibility, but these “failures” are less visible to the casual observer.
Online Reviews
Product reviews on e-commerce sites can be affected by survivorship bias. People who have extreme experiences (very positive or very negative) are more likely to leave reviews. This can create a bimodal distribution that doesn’t accurately reflect the average user experience.
The Psychology Behind Survivorship Bias
Understanding why we’re prone to survivorship bias can help us combat it more effectively. Several psychological factors contribute to this bias:
Availability Heuristic
We tend to base our judgments on information that’s readily available to us. Successes are often more visible and memorable than failures, making them easier to recall.
Confirmation Bias
We have a tendency to search for, interpret, and recall information in a way that confirms our preexisting beliefs. If we believe in a particular path to success, we’re more likely to notice and remember examples that confirm this belief.
Narrative Fallacy
Humans are natural storytellers, and we often create coherent narratives to explain complex events. Success stories often make for compelling narratives, while stories of failure may seem less interesting or instructive.
Optimism Bias
Most people tend to overestimate their chances of positive outcomes. This natural optimism can make us more susceptible to survivorship bias, as we’re predisposed to focus on success stories.
Conclusion: The Importance of Critical Thinking
Survivorship bias is a subtle but powerful force that can shape our perceptions and decisions in significant ways. From business strategies to personal life choices, this cognitive error can lead us astray if we’re not vigilant.
The key to overcoming survivorship bias lies in cultivating critical thinking skills and maintaining a healthy skepticism. We must train ourselves to look beyond the obvious, to question our assumptions, and to seek out the less visible data points that might tell a different story.
By understanding and accounting for survivorship bias, we can make more informed decisions, develop more effective strategies, and gain a more accurate understanding of the world around us. Whether we’re analyzing historical events, evaluating business opportunities, or simply trying to learn from others’ experiences, keeping survivorship bias in mind can help us avoid pitfalls and arrive at more robust conclusions.
In a world where success stories are amplified and failures often fade into obscurity, the ability to see beyond survivorship bias is more than just an intellectual exercise – it’s a crucial skill for navigating the complexities of modern life. By broadening our perspective to include both the survivors and the unseen casualties, we can gain a more nuanced and accurate view of reality, leading to better decisions and a deeper understanding of the world around us.
