04 — Research · Psychological delta
The performance you are hiring for is already on your payroll
Roughly half of the differences in job performance sit inside the same person — between their better and worse weeks — not between one person and the next. Hiring cannot reach that half. This page is about the half that is already yours.
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The Gap Inside You
A short talk on why the performance you are trying to hire is often already inside your teams — and how to reach it.
Filmed September 2026, after presenting this research at the XIX Vanguard Scientific Instruments in Management conference.
- 40–65%
- of the differences in job performance sit inside the same person, not between peopleDalal, Alaybek & Lievens (2020), Annual Review of Organizational Psychology and Organizational Behavior
- 18%
- is what the strongest hiring procedure we have — the structured interview — predicts about the differences between peopleSackett et al. (2022), Journal of Applied Psychology
- 71%
- of lost productive time comes from people who are at work but performing below their level, not from absenceStewart et al. (2003), Journal of Occupational and Environmental Medicine — US study of health-related lost productive time
Synthesised in Psychological Delta (Balabanov, 2026). See the evidence →
The construct
The psychological delta
I call that within-person half the psychological delta. It breaks into four quantities you can actually observe in your own organisation.
- Δ-peak
- Δ-peak: the distance from a person’s typical day to their best day. This is the reserve. Unlike a candidate’s potential, it is not a prediction: the good days have already happened, in your organisation, on this job.
- Δ-total
- Δ-total: the full range, read together with the average. A wide range around a high average is flexibility. A wide range around a low average is exposure.
- Δ-floor
- Δ-floor: the distance from typical down to their worst day. This is what fatigue, stress and friction cost, and it is where presenteeism is paid for.
- Recovery
- Recovery: how fast the person returns to their typical zone after a bad stretch. Of the four, this is the one leaders influence most and measure least.
Tap a label above to see what each part means.
The sentence to keep.
In a labour market where nearly three in four employers cannot buy the performance they need, the largest untapped source of performance is not on the market at all. It is the distance between the versions of the people already hired.
The paper
Psychological Delta: The Within-Person Performance Reserve and the Limits of the External Talent Market
By Alexander Balabanov, PhD (DynamixLab Ltd). Presented at the XIX Vanguard Scientific Instruments in Management conference, September 2026. The full paper follows once the journal's review is complete.
A four-page executive brief, written for HR leaders in small, tight labour markets, is available on request.
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Find out how much of the reserve your organisation can reach.
The Performance Reserve Diagnostic applies this research to your own teams in 3 weeks, starting with data you already hold.
Sources: Dalal, Alaybek & Lievens (2020), Annual Review of Organizational Psychology and Organizational Behavior · Stewart & Nandkeolyar (2006), Personnel Psychology · Sackett et al. (2022) and Sackett, Zedeck & Fogli (1988), Journal of Applied Psychology · Stewart et al. (2003), Journal of Occupational and Environmental Medicine · Mark, González & Harris (2005), CHI · Arthur et al. (2003) and Lacerenza et al. (2017), Journal of Applied Psychology · Frazier et al. (2017), Personnel Psychology · Eurostat (2026) · Central Bank of Malta (Borg 2025; Grech 2023) · FHRD & PwC HR Pulse Survey 2025 · Balabanov (2025, 2026). Full reference list in the paper.