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Miriam TzeqavriChief Data Officer

The journal · Matching evaluation

Better matching precision does not erase the missed people

A stricter threshold can reduce false links while leaving more genuine pairs disconnected. A useful recommendation explains both errors and the operating work they create.

A matching evaluation often arrives with one percentage in large type. The figure may be correct and still leave the decision-maker without enough evidence to choose a handling approach. A rule can become more precise by making fewer links, including fewer wrong ones. It can also leave more genuine same-person pairs unconnected. Neither consequence disappears because one measure has improved. The recommendation needs to explain what kind of mistake is changing and what the organisation will do with the records affected by it.

In our fictional 2024 exercise, reviewers labelled 1,000 record pairs: 660 as the same person and 340 as different people. The looser rule linked 700 pairs, with 630 supported same-person links and seventy false links. It missed thirty genuine pairs. The stricter rule linked 610, with 600 supported links and ten false ones, but missed sixty genuine pairs. The stricter result was attractive for a good reason. It also carried a cost that deserved to remain beside the attractive number.

Begin with the two mistakes

Precision asks what share of the proposed links is supported as correct in the evaluation. The looser rule achieved 630 out of 700, or 90%. The stricter rule achieved 600 out of 610, about 98.4%. Recall asks what share of the 660 same-person pairs was found. That moved from approximately 95.5% to 90.9%. These measures describe different questions. Selecting the more flattering one does not make the other irrelevant to the workflow.

The consequences also differ. A false link can combine information about people who should remain separate. A missed link can require additional searching, clarification or repeated handling. The actual seriousness depends on the use. A research comparison, a service lookup and a decision affecting a customer do not necessarily justify the same approach. The data team should make those consequences explicit rather than treat the preferred threshold as a purely mathematical choice that operating owners simply inherit.

I do not assume that every false link has already produced harm. In this exercise, the counts came from a reviewed evaluation set. They were not a report of live claims decisions or actual disclosures. Equally, I would not describe missed links as harmless administrative inconvenience without examining the service route. A person can experience the cost of fragmented information even when no incorrect merge occurs. The useful discussion takes both possibilities seriously without manufacturing outcomes the evidence has not established.

Our sponsor wanted the higher precision figure to support an unattended rollout. Rina and I recommended an assisted pilot with a ₹1.3 crore allocation for implementation and review. The choice reflected the proposed purpose and the consequences of wrong connections. It did not establish that the stricter rule was intrinsically best for every setting. We retained both error accounts in the recommendation and made the remaining handling work part of the operating discussion, rather than presenting it as a problem for someone else after approval.

The sample defines the claim

A reviewed sample is necessary for this kind of comparison, but it does not automatically represent every future record. The proportions of same-person and different-person pairs matter, as do the kinds of spelling variation, shared contact and incomplete evidence present. A performance claim should describe the population and labelling process on which it rests. Otherwise a precise percentage can encourage a much broader inference than the exercise was designed to support.

The review labels deserve scrutiny as well. Calling them the reference does not make them infallible. I want to understand the evidence available to reviewers, how disagreements were handled and which pairs could not be settled. In the stated exercise, the 1,000 pairs carried reviewed labels for the comparison. That does not justify forcing every ambiguous live pair into one of the two classes merely because the evaluation table has only two columns. A production handling route may need a visible unresolved state.

There is also a risk of improving the reported number by repeatedly selecting a threshold against the same familiar examples. A team can learn the evaluation set without demonstrating the same performance elsewhere. This essay does not claim that such a problem occurred in our fictional exercise. It is a reason to ask how an evaluation is used and what further examination is needed before relying on the result. A leadership account should identify that remaining work rather than allow the apparent precision of the calculation to stand in for it.

When an operating environment changes, the comparison may need revisiting. New partners, different intake practices or a greater share of assisted customers can change the relationships represented by a field. The system does not acquire permanent authority from one favourable review. I want a defined responsibility for examining whether the evidence behind the chosen rule remains relevant to its actual use. That is part of the continuing cost of a matching service, not an optional refinement after launch.

Choose a handling route, not just a percentage

Under the stricter rule, 390 of the 1,000 evaluated pairs were not linked automatically. They included sixty same-person pairs and 330 different-person pairs according to the review. An unlinked output therefore could not be translated directly into a finding that the parties were different. The operating route needed to explain when further evidence or assistance was appropriate. A threshold supplies an output; the organisation still owes the user a coherent account of what happens next.

The pilot allocation supported that wider handling design. It was not proof of measured production improvement or a saving already achieved. We accepted additional reconciliation work and retained examination of both error types. Claims, underwriting and other professional owners remained responsible for the decisions their functions made. A matching result could assist a search without becoming an automatic instruction to change cover, delay a payment or take an adverse action against a customer.

I would judge the recommendation by whether another executive could explain the sacrifice it makes. In this case, fewer false links in the reviewed set came with more missed matches and more work outside the automatic path. That can be a sensible choice, but it needs a reason grounded in the actual purpose. A cautious-sounding threshold is not a substitute for judgement any more than a high percentage is a substitute for evidence.

The practical discipline is to keep the people behind both errors in the discussion. Ask who might be connected incorrectly, who might remain fragmented and how either situation can be examined. Then describe the chosen route, its evidence and its limits in terms the approving body can use. A matching percentage is valuable when it sharpens that decision. It becomes misleading when it allows the organisation to forget the cases that the headline does not count as success.