Several familiar patterns can overlap
Confirmation bias favors evidence that supports an existing belief. Anchoring gives an initial number excessive influence. Hindsight makes an outcome feel more predictable after it occurs. Loss aversion concerns the different psychological weight people can attach to losses and gains.
These descriptions do not diagnose an individual or explain every decision. Context and incentives matter too. A person can correctly identify a bias in someone else’s argument while showing it in their own analysis.
An original research-room example
Imagine an analyst expects a fictional company’s margins to improve. The analyst highlights a favorable product announcement, dismisses a documented increase in costs and keeps repeating an old price target. The question is not whether the analyst is optimistic; it is whether contradictory evidence receives a fair assessment.
A written thesis can require reviewing both the cost data and the product claim against pre-specified conditions. That does not guarantee an unbiased result, but it makes selective evidence easier to notice and discuss.
A good result can follow a poor process
Suppose a decision made with weak evidence happens to earn a profit. That outcome does not prove the reasoning was sound. Likewise, a carefully researched decision can lose money because uncertainty was real. Evaluating only winners can train a process to repeat mistakes that were temporarily rewarded.
A record made before the outcome helps distinguish the original information from the later story. Keep assumptions, alternatives and what would change the view. Do not revise the historical reasoning until it looks as if the result was obvious all along.
Build checks into the workflow
Separate facts from estimates, examine an opposing explanation and state the baseline for comparisons. Use the same standard for evidence that supports and challenges a view. Revisit the decision process as well as its return.
The purpose is not to eliminate emotion by declaration or claim that one checklist makes someone rational. It is to create a process in which errors can be recognized and corrected. These habits apply when reading a newsletter just as they do when constructing an investment thesis.
An analyst notices evidence against a thesis and ignores it solely because the original forecast must be right. Which problem does that illustrate?
Show the explanation
It illustrates confirmation bias and belief perseverance. The corrective step is to evaluate the contradictory evidence against a stated thesis, rather than protect the forecast from testing.
Sources and editorial notes
Original explanations and hypothetical examples prepared with AI assistance. Primary references checked October 16, 2026. Numerical examples are hypothetical unless explicitly identified otherwise.
- CFA Institute: The Behavioral Biases of Individuals
Cognitive and emotional biases, evidence processing and mitigation concepts.