Organisations that change hiring practice often report improvement at entry level and almost none at the top. The gap is largely arithmetic, and understanding it clarifies what any policy can achieve.
Senior seats turn over rarely
A leadership team holds a small number of positions, and each occupant may stay for many years. Only a handful of appointments occur in a typical year.
With few decisions available, even a substantial change in who is appointed alters the overall composition slowly. The denominator is fixed and the numerator moves by ones.
Entry-level hiring is the opposite case. Large intakes recruited annually allow composition to shift quickly, which is why the two levels appear to respond to the same policy differently.
Pipelines carry a long delay
Senior candidates are usually drawn from a pool that has accumulated a decade or more of experience. That pool reflects hiring decisions taken long before the current policy existed.
A change at entry today therefore reaches the senior candidate pool only after the cohort has advanced through intermediate stages, each with its own attrition.
Because the delay is measured in years, organisations reviewing annually observe no movement and sometimes conclude the intervention failed when the cohort has simply not arrived yet.
Attrition compounds at each stage
Progression is a sequence of filters, and a modest difference in advancement rate at each one produces a large difference by the final stage.
Departure rates matter as much as promotion rates. A group promoted at the same rate but leaving faster will still be thinly represented at the top.
Exit interviews and retention data are therefore more informative than recruitment figures for diagnosing where a pipeline loses people, though they are collected less consistently.
Selection criteria reproduce the existing shape
Senior appointments frequently rely on informal reputation, sponsorship and networks. These channels transmit information efficiently but tend to circulate within groups that already hold positions.
Criteria such as continuous service or willingness to relocate at short notice appear neutral yet correlate with caring responsibilities, which are unevenly distributed.
Structured processes with defined criteria and wider candidate searches change who is considered. The effect is gradual because it applies only to each vacancy as it arises.
What the numbers can and cannot show
Because senior counts are small, a single appointment or departure moves the reported figure noticeably. Year-to-year changes are dominated by that volatility rather than by trend.
Tracking promotion and retention rates by stage gives a more reliable picture, since those rates are calculated over larger groups and respond sooner to changed practice.
Reporting obligations and permitted data categories differ by jurisdiction, so what an organisation can measure and publish is partly determined by where it operates.