The Streetlight Effect for HR: Why We Measure What's Easy and Ignore What Matters
Behavioral scientists call it the Streetlight Effect: searching for keys under the streetlight because that's where the light is.
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- Streetlight Effect: bias toward measuring what's easy, not what's important.
- HR is structurally exposed: it inherits HRIS-easy numbers and ignores latent, important ones.
- Result: dashboards full of vanity metrics; the questions the CEO actually asks have no answer.
- Fix: start with the question, not the data. Build the metric backwards from decision.
- For tech: it's the analytics anti-pattern of optimizing what's logged instead of what's valuable.
An HR team built a 14-tab dashboard: headcount, time-to-fill, training hours, eNPS, attrition, diversity ratios. The CEO opened it once a quarter and asked a question it couldn't answer: 'Which of the people I most don't want to lose are most likely to leave in the next 6 months?' That question requires regrettable-attrition prediction. The dashboard had none of it — because it's hard.
Where the bias comes from
“A man searches for his keys under a streetlight, though he lost them in the dark. Asked why, he says: 'because this is where the light is.'”
HR inherits an HRIS schema designed for compliance and payroll. The easy metrics — headcount, tenure, completion, time-to-X — are pre-built. The hard metrics — skill transfer, belonging, regrettable attrition, network health, decision quality — require new instrumentation. Under deadline pressure, dashboards default to the streetlight.
HR's brightest streetlights (and what's actually in the dark)
| What's measured (lit) | What matters (dark) |
|---|---|
| Training hours | Skill transfer 30/60/90 days later |
| eNPS / engagement | Belonging, voice, psychological safety |
| Time-to-fill | Quality + 12-mo retention of hire |
| Aggregate attrition % | Regrettable attrition by performance tier |
| Diversity headcount ratios | Inclusion experience by intersection |
| Manager 1:1 completion | Manager coaching quality (sampled) |
Working in the dark
- Start with the decision: 'What will we do differently if this number is high vs. low?' If no answer, don't build the metric.
- Inventory the top 5 questions the CEO actually asks. Build instrumentation for those, in priority order.
- Use proxies cautiously: 'manager coaching quality' is hard, but skip-level sentiment + IC growth velocity is a defensible composite.
- Sampling beats census for hard metrics: 80 high-quality interviews on belonging beat 4,000 survey responses.
- Set a 'dark/light ratio': at least 30% of your reported metrics should be ones that didn't exist 12 months ago.
Audit your last quarterly HR report. Count metrics. How many directly answer a real executive decision? In most companies the answer is <30%. The rest is streetlight light.
Tech analog
Analytics teams know this trap: you instrument what's easy in your event pipeline, then optimize what you instrumented, even when the lever that matters lives off-platform. The discipline of 'metrics from decision, not from data' is what separates senior analytics work from junior. The same applies to People Analytics.
Takeaways
- Easy metrics dominate because they're easy, not because they matter.
- Build from the decision backwards. If no decision changes, kill the metric.
- Spend 30% of People Analytics effort instrumenting things that didn't exist a year ago.
- Freedman — Why Scientific Studies Are So Often Wrong: The Streetlight Effect — Discover Magazine, 2010
- Kahneman — Thinking, Fast and Slow (availability heuristic) — FSG, 2011
- Google re:Work — People Analytics — Google
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