In Noise: A Flaw in Human Judgment, Daniel Kahneman, Olivier Sibony, and Cass Sunstein explain bias and noise using a target analogy.
Bias is like consistently hitting the same wrong spot on a target. Your shots are tightly grouped, but off-centre. This represents a systematic error—judgments are predictably skewed in one direction, such as consistently favouring certain types of candidates.
Noise is like shots scattered all over the target. There’s no consistent pattern—some hit near the centre, others far away. This reflects inconsistency in judgment, where different people (or the same person at different times) make different decisions about the same case.
The key difference is that bias affects accuracy, while noise affects consistency. A system can have one, the other, or both—for example, recruiting decisions might be both biased and inconsistent.
While bias is more visible and often addressed, noise is frequently overlooked. Reducing bias requires correcting directional errors, whereas reducing noise requires structured processes that make judgments more consistent.
Recruiting decisions feel personal, intuitive, and even instinctive but they are often far less reliable than we think. Chapter 24, “Structure in Recruiting,” challenges the way most organizations recruit and argues for a more disciplined, structured approach.
In recruiting, Noise shows up when different interviewers evaluate the same candidate in completely different ways. Traditional, unstructured interviews—where questions vary and decisions rely on gut feeling—are especially prone to this issue. Two managers might walk away from the same conversation with opposite conclusions, not because the candidate changed, but because their judgments are inconsistent.
This inconsistency is amplified by cognitive biases. Interviewers are often influenced by first impressions, likeability, or similarities in background. A candidate who seems confident or relatable may be rated more highly, even if those traits are irrelevant to job performance. The halo effect can cause one positive quality to overshadow weaknesses, while confirmation bias leads interviewers to seek evidence that supports their initial impression. The result is a process that feels insightful but is actually driven by subjective and often unreliable factors.
Despite these flaws, many of us remain confident in our ability to “read people.” This confidence reflects what the authors describe as the illusion of validity. After an interview, it’s easy to construct a compelling story about why a candidate would succeed or fail. These narratives feel convincing, but they are often based on limited information and shaped by bias. The more coherent the story, the more confident the interviewer becomes—even if the judgment itself is flawed.
So what’s the alternative? The authors advocate for structured recruiting, a method designed to reduce both noise and bias. Instead of relying on intuition, structured recruiting treats recruitment as a measurement problem.
The first step is to break down the role into specific competencies—such as problem-solving, communication, or teamwork. Candidates are then evaluated against these criteria individually, rather than being judged on an overall impression. This helps ensure that relevant factors are considered systematically.
Next comes standardization. All candidates should be asked the same questions, and their responses should be rated using predefined scales. This makes comparisons fairer and reduces the variability (noise) caused by different interview styles. Structured processes often include additional tools like work sample tests, which provide direct evidence of a candidate’s ability to perform the job.
Another key principle is independence. Interviewers should assess candidates separately, without discussing their opinions beforehand. This prevents groupthink and ensures that each perspective is captured. Only after all evaluations are complete should the results be combined into an overall judgment.
Delaying that final judgment is crucial. In unstructured interviews, people tend to form quick opinions and then interpret everything else through that lens. Structured recruiting forces decision-makers to consider all the evidence before reaching a conclusion, leading to more balanced and accurate assessments. This method defers our decision making until more structured information is available to our intuition.
The payoff is significant. Structured recruiting reduces inconsistency, limits bias, and improves the ability to predict job performance. It also creates a fairer process for candidates, as everyone is evaluated using the same criteria.
The takeaway is that it improves our decision hygiene.