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Bias

As explained in Effective Data Analysis

Bias is a systematic pattern of error or unequal treatment that produces unfair or disadvantageous outcomes for particular groups.

Bias is a systematic pattern in data, rules, or decisions that disadvantages particular groups. In analytics, it matters whenever a report or automated system influences how people are evaluated or treated. Apparent objectivity does not guarantee a fair outcome. section 8.0 section 8.2.2

Hiring from historical resumes

A resume-ranking model trained on past applicants learned from a pool heavily weighted toward men. It gave lower scores to applicants who attended women’s colleges or mentioned “women.” Attempts to remove the gender bias failed, and the project was abandoned. The case also exposes a harder question: recruiters and teams do not share one measure of candidate quality. section 8.0

Bias is not limited to machine learning. A rules-based system can have unintended effects when its designers miss how a rule applies to people; a learned system can reproduce patterns in its training data. Neither approach should be assumed fair merely because it applies rules consistently or handles many records. section 8.2.2

Customer-support triage

A support team considers rules-based and supervised models to assign ticket types and priority levels. Because those labels determine queue order and response speed, a categorization system that streamlines work could also have an unanticipated negative effect on certain customer groups. Accuracy alone does not settle the question of impact. section 8.2.2

Treat biased output as a decision risk, not just a technical defect. Ask whose data shaped the system, which groups may be affected, and whether the resulting decisions can be trusted. The concern extends to large language models trained on human data; biased output has been noted in consequential areas such as healthcare. Automated hiring tools may also face bias-audit requirements. section 8.0 section 8.4 section 12.4.2

How Effective Data Analysis covers it

How deep it goes
Explains historical data and designer rules as bias pathways through applied cases, without providing an audit procedure or fairness metric.
Examples
Uses a resume-ranking failure and customer-support ticket categorization to show how biased outcomes can affect people.
What you can do after
Evaluate/understand it by questioning training data, subgroup impacts, and whether an automated decision can be trusted.
How it connects
Connects bias to automated decision systems, sensitive data, and large language models.

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This explainer was generated by Manning's knowledge graph from the text of Effective Data Analysis. The section links point to the parts of the book it draws on.