Predictive models can lose the plot. Here's how to keep them on track
Bibliographic record
Abstract
Organizations are increasingly turning to sophisticated data analytics algorithms to support real-time decision-making in dynamic environments. However, these organizational efforts often fail—sometimes with spectacular consequences. In 2018, real-estate marketplace Zillow launched Zillow Offers, an “instant buyer” arm of the business that leveraged a proprietary algorithm called Zestimate, which calculated the estimated sales prices of real estate. Based on these calculations, Zillow Offers planned to purchase, renovate, and resell properties for a profit.1 While it had some success for the first few years, the model failed to adjust to the new dynamics of a more volatile market in 2021. Zillow lost an average of $25,000 on every home they sold in the fourth quarter of 2021—resulting in a write-down of $881 million.2 This is an instance of what we call algorithmic inertia: when organizations use algorithmic models to take environmental changes into account, but fail to keep pace with those changes. Here, we explain algorithmic inertia, identify its sources, and suggest practices organizations can implement to overcome it.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.021 | 0.109 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.004 | 0.013 |
| Scholarly communication | 0.021 | 0.048 |
| Open science | 0.004 | 0.009 |
| Research integrity | 0.009 | 0.029 |
| Insufficient payload (model declined to judge) | 0.023 | 0.016 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".