Lesson Summary:

Algorithms are mirrors: they reflect what we feed them. In this lesson you’ll trace the journey from raw data to real-world impact, uncovering how skewed or incomplete training sets spawn biased outcomes—from unfair loan denials to faulty facial-recognition arrests.

Data Is Destiny: Why the Training Set Matters

Imagine training a sommelier on only two wines—both sweet, both cheap. Every future bottle, no matter how rich or subtle, would be judged against that narrow palate. Algorithms work the same way. Feed them skewed or incomplete data and they’ll echo those distortions at industrial scale.

  • Weights & patterns form atop the data we choose (or overlook).

  • Feedback loops amplify early mistakes—especially when decisions feed back into new training data.

  • Real people feel the consequences: mortgage rejections, misidentified suspects, or medical risk scores that miss entire communities.

Bias in the Wild: Three Quick Vignettes

  1. Healthcare Risk Scores – A widely used algorithm underestimated Black patients’ needs because cost, not illness severity, was its proxy metric. Result: fewer referrals for critical care. 

  2. Resume-Screening LLMs – State-of-the-art models ranked “Emily” higher than “Lakisha” despite identical credentials, reflecting historical hiring bias. 

  3. Facial Recognition Arrests – Misidentification rates on darker-skinned faces led to wrongful detentions, spotlighting systemic flaws in training datasets.

How racial biases in medical algorithms lead to inequities in care - PBS NewsHour | Dec 17, 2022

Detroit woman sues Detroit Police Department after arrest over false facial recognition match - CBS Detroit | Aug 8, 2023

Timeline of Notable AI Bias Incidents From 2015 to 2025, major examples across sectors. 2015 • COMPAS 2019 • Optum Risk Scores 2023 • Stable Diffusion Stereotypes 2024 • LLM Hiring Bias 2025 • Ageism in Care Bots

A Timeline of Bias