What the log cannot see

Avoidance

The largest gap, and by its nature unmeasurable. Before treating a quiet week as proof that the arrangement works, managers can compare the available evidence settings and define which delayed workload patterns would trigger a closer review.

A collision is recorded when somebody moves. Nothing is recorded when somebody does not come into a room because they can hear a call through the door, or does not start cooking because somebody is working at the table, or waits forty minutes before putting a wash on. For wider context beyond this household record, consult material published by RTINGS.com.

The log contains four instances where avoidance was mentioned out loud and therefore noted. It cannot contain the ones that were not mentioned, and those are almost certainly the majority.

Every successful avoidance is a collision that did not happen and also a thing somebody did not do.

If avoidance is common — and the household's own account says it is — then a low collision count can mean a well-arranged flat or a household that has learned to stay out of each other's way. The number does not distinguish them.

Degradation

Working at a folding table in the living room is working. It is not working as well, and nothing in the log says so.

Thirty-five minutes in another room is recorded as thirty-five minutes in another room. Whether the thirty-five minutes produced anything is outside what the method can reach, and attempts to record it in the first days of the fortnight were abandoned because the judgements were not stable between the two people or between days.

The evening

The log covers waking hours and treats them alike. It does not distinguish between an interruption at eleven in the morning and one at seven in the evening.

Both people say the evening ones were worse. The reason given is not about the work: it is that an evening interrupted by work is an evening that did not happen, and the log has no column for that.

Six of the forty-seven occurred after six in the evening. On the household's account those six account for most of what they would describe as strain, and in the record they are six out of forty-seven, indistinguishable from the rest.

The accumulation

The log treats each collision as an event. It does not record whether a day with four of them is worse than four days with one.

This matters because the distribution is not even. Three days in the fortnight carried seven or more collisions each; four days carried one or none. If the cost is in the clustering rather than the count, the record's central number is measuring the wrong thing entirely.

The log cannot settle that, and the household's view is divided: one of the two describes the bad days as much worse than the sum of their parts, the other does not.

Why publish it anyway

Because a method with stated blindnesses is more useful than a better method that nobody applied.

The forty-seven are real, they are checkable against a stated test, and the finding that rests on them — the distribution between two people — holds under every alternative accounting tried, including removing the welcome collisions and removing the evening ones.

What should not be done with the number is treat it as a measure of how hard working at home is. It measures how often one activity took a room from another in one flat over fourteen days, which is a smaller and more honest thing.

The fifth thing: what was not attempted

Beyond avoidance of rooms, there is avoidance of activities, and it is invisible by the same mechanism.

Three instances surfaced in conversation after the fortnight and none is in the log.

Somebody did not start a piece of work that needed two uninterrupted hours, and did it at the weekend instead. Somebody did not invite a friend round on a weekday, having previously done so. Somebody did not cook something that takes an hour of attention.

In each case nothing gave way, nothing moved rooms and nothing was displaced, because the activity never began.

That is the deepest form of the blindness. A dwelling under pressure does not only produce collisions; it produces a household that has quietly stopped doing the things that would cause them, and a log of collisions records the adaptation as an improvement.

Why the record was published anyway

A method with stated limits is more useful than a better method nobody applies, and there is a specific reason to think the limits do not undermine the finding.

Every blindness listed on this page hides costs. Avoidance, degraded work, evenings, clustering, things not attempted — all of them would push the collision figure up if they could be seen.

None of them obviously affects the split between the two people, which is what the site actually concludes from. If anything, the household's account suggests avoidance runs the other way — the person with the calls staying out of the kitchen in the morning — which would move the distribution toward even and against the finding.

So the record understates the cost and may slightly overstate the imbalance, and both of those are stated rather than discovered by a reader.