The glass ceiling is one of the most successful metaphors in the language of workplace equality. It is also, according to the pipeline data collected over the last decade, describing the wrong floor.
What the data shows
Large-scale studies tracking representation at each level of corporate hierarchies have found a consistent pattern.
Entry-level representation is close to parity in many sectors. Representation at the first management level is substantially lower. And each subsequent level declines further, but by smaller proportional amounts than the first step.
The implication is arithmetic. If a cohort is depleted at the first gate, every subsequent level draws from an already-reduced pool. A pipeline that loses a disproportionate share at step one will show a small number at step six regardless of how fair steps two through six are.
This does not mean discrimination at senior levels does not exist. It means that fixing it alone cannot produce parity, because the population it operates on has already been determined.
Why the metaphor matters practically
The two framings imply different interventions, and organisations have spent heavily on the wrong one.
A ceiling framing implies board quotas, executive sponsorship programmes, senior leadership targets and visibility initiatives — all aimed at the top of the structure.
A broken-rung framing implies examining how first-line managers are selected, who is given supervisory experience, how "readiness" is assessed, and what the criteria for the first promotion actually are.
The second set is less visible, involves middle managers rather than executives, and produces no photographs. It is also the one the data points at.
Why the first promotion is different from the others
Several features of the first promotion make it unusually vulnerable to unexamined judgement.
It is a change of kind, not of degree. Later promotions assess someone's performance as a manager. The first assesses whether someone would be a good manager, which is a prediction rather than an observation.
Predictions rely on assessed potential. The distinction between promotion on performance and promotion on potential recurs throughout this literature, and analyses have found that men are more often advanced on assessed potential while women are more often advanced on demonstrated performance. That asymmetry has an obvious effect at the one gate where nothing has yet been demonstrated.
The decision-maker is usually a single line manager. Later promotions typically involve committees and documented processes. The first is often one person's recommendation, made informally, with little scrutiny.
Readiness signals are behavioural. "Ready for management" is frequently assessed on things like taking charge in meetings and confident self-presentation — precisely the behaviours the calibration literature suggests are unevenly displayed and unevenly received.
What organisations have found when they looked
Firms that have audited first-promotion decisions have generally found the pattern in their own data, and have often been surprised, because it is invisible without the aggregation.
A single manager promoting one of three candidates makes a defensible decision. The same pattern repeated across two hundred managers produces a statistical result that none of them intended and none of them can see.
This is the recurring structure in workplace inequality research: outcomes that look like a policy but were produced by an accumulation of individually reasonable judgements.
Interventions with some evidence
Structured promotion criteria specified in advance. The evidence on structured versus unstructured evaluation is reasonably strong and consistent in direction.
Requiring diverse slates for management openings. Some evidence suggests that when only one candidate from an underrepresented group is considered, the probability of selection is very low, and that this changes when more than one is on the list.
Making the promotion process opt-out rather than opt-in. Where advancement requires self-nomination, the self-assessment gap operates directly. Where all eligible employees are automatically considered, it does not.
Auditing at the manager level rather than the organisation level. Aggregate figures conceal enormous variation between managers, and the variation is where the actionable information is.
Separating performance review from potential assessment, and requiring evidence for the latter.
The counterintuitive implication
Board-level targets — the most publicly visible intervention — have some real effects on the composition of boards and on visibility, but they cannot fix the pipeline, because board members are frequently recruited externally and from a small pool.
An organisation that meets a board target while its first-promotion ratio remains skewed has changed its top layer and nothing about its structure. Several years later its internal senior pipeline will look the same as before.
This is not an argument against the visible interventions. It is an argument that they are being asked to do work they cannot do, and that the unglamorous audit of who becomes a team leader has better leverage than anything happening in the boardroom.