Short answer
An aggregate stops protecting anyone once the group behind it is small enough to guess. The floor commonly held is five respondents: below that, a number broken down by team, by site or by tenure becomes attributable again, and the more filters combine, the faster it happens. The threshold has to be set before collection, because once the results are on the table the wish to look always wins the argument against the rule.
What an aggregate actually protects
An aggregate protects nobody by nature. It protects when the group it covers is wide enough that no one inside it is recognisable, and it stops the moment that group narrows. The difference has nothing to do with how the data was gathered and everything to do with the size of the last slice shown on screen.
The risk almost never comes from a single number. It comes from filters stacking. A department of thirty raises no question at all. The same department filtered by site, then by tenure, then by contract type sometimes leaves two people behind the average, and everyone in the room knows which two.
Four harmless breakdowns, taken together, point at a person as surely as a name does. That is why the floor applies to the cell being displayed, never to the population that was asked.
Why five, and why beforehand
Five is not a mathematical constant. It is a legible compromise: low enough that a frontline team still exists in the results, high enough that one response does not stand out on its own. An organisation that prefers six or eight protects more and loses granularity. What matters is that the number holds.
What matters more than the number is when it was fixed. A floor decided before collection is a rule. A floor discussed afterwards, in front of a table with one interesting cell missing, is an exception that becomes the norm on the next round.
The question asked at that moment is always the same, and it is always reasonable: this site only has three respondents, can we look anyway? The answer needs to have been written down before anyone wanted to ask it.
What the floor demands of reporting
Holding a floor changes how results travel, and that consequence is better anticipated than discovered.
- A cell below the floor is not shown, and must not be recoverable either: if the total and every other cell are visible, the hidden one can be worked out by subtraction.
- Grouping beats masking wherever it is possible, merging two small teams rather than leaving a hole.
- Managers receive what concerns them in a form they can act on, never the raw words of their teams.
- The floor applies to quotes as well, which are the most common leak: a recognisable sentence identifies better than any number.
- What is hidden is announced as hidden, with the reason. A table that conceals without saying so makes people doubt everything else on it.
That last rule is the one most often forgotten. A team that discovers by accident that part of its results was quietly withheld will conclude that other things are being withheld too, and the next response rate will say so.
A floor is not a promise
A technical floor is a guarantee, not a commitment. It stops a person being reconstructed from a table. It says nothing about what will be done with the answers, who will read them, or what comes back down afterwards.
At Lontra the separation is explicit: signals inform human decisions, they do not replace them. Nothing collected is used to monitor anyone or to score a person, and managers never hear the raw conversations.
The promise kept is worth more than the number chosen. An organisation that announces five and applies five earns more trust than one that announces ten and makes an exception for the first executive committee that asks.
For the way a conversation differs from a questionnaire when results come back, see our resources on reporting.