The Empty Spreadsheet and Vietnam Swimming's Un-Regressed Lane

At 2:47 in the morning in Hai Phong, the screen returned an extraction file that had just finished running. Every cell was empty: no title, no source, an empty list of information points, a blank assessment section. Twelve analytical categories, twelve lines reading "insufficient information to assess."

In the newsroom the reaction was familiar: if there is nothing, what do we publish? I read it the other way around. An empty table is the biggest data point of the day, because it says exactly one thing: the measurement chain broke somewhere, and nobody in the production line noticed.

With swimming, I have been used to this scene longer than I would like to admit.

I grew up beside the lane. In the early years of my career I wrote about swimming, and the job taught me a habit: before trusting a result, go and find the split sheet. At an international meet with standards, that sheet exists. At most domestic meets, it does not, and that emptiness gets read as "nothing to talk about."

The data foundation of a sport

Vietnamese swimming has just passed through a decade carried on one pair of shoulders. Nguyen Thi Anh Vien was the name that held most of the regional expectation for years. After she stepped away from elite competition, the question "who is next" appeared on every sports page. Nguyen Huy Hoang has secured Olympic berths in the 800m and 1500m freestyle, appearing at the most recent Games. Tran Hung Nguyen anchors the medley group. Pham Thanh Bao represents the breaststroke line.

The media story compresses into one sentence: Vietnamese swimming is rising. I will not argue against it with medals, because medals are the easiest thing to count and the easiest thing to mis-count. I want to test whether that proposition can even be verified.

To do that, you have to establish which layer the data sits on. I divide it into three.

Layer one is aggregated public data: medal counts, national records, entry lists. Vietnam has this layer, at acceptable quality.

Layer two is semi-public data: 50m splits, starting reaction times, entry counts by age group for each event. Vietnam has part of it, and most of it lives scattered in coaches' notebooks rather than in a public file.

Layer three is internal data: stroke rate, distance per stroke, the turn-and-underwater segment inside the final 15m, training load, injury history. This layer is almost never published. Singapore, Japan and Australia publish all three layers.

The distance between Vietnam and the regional leaders is not in layer one. It is in layers two and three.

Why splits decide everything

In 2026, in a World Cup round-of-16 match in Russia, I used a PPDA of 8.7 to show that the host team was not defending passively the way the press described. They were actively pushing opponents to the flanks. That number never appeared on the scoreboard, but it explained the scoreboard.

Swimming has an equivalent number, and it never appears on the results sheet either: the 15m turn-and-underwater phase after the start. This is the zone where most races are won and lost, and it is also the zone where Vietnamese data is almost blank.

Take an illustrative example, not a real result. Two 200m freestyle swimmers touch in 2:04.0. Swimmer A splits 28.5 - 32.0 - 32.2 - 31.3. Swimmer B splits 29.8 - 31.4 - 31.5 - 31.3. Identical totals. The results sheet prints two identical lines.

But these are two fundamentally different athletes. A lives on starting speed and dies at the 150m mark. B distributes effort evenly and finishes stronger. A needs a block of speed-endurance work. B needs front-end power. With only the total time, a coach prescribes the same programme to both, and one of them regresses without anyone knowing why.

This is why I do not treat missing data as a minor inconvenience. Missing data does not slow anyone down. It only makes mistakes invisible.

Reaction time is another example. At meets sanctioned to World Aquatics standards, the figure is published. Domestically, almost never. Nobody knows whether 0.72 seconds is normal or poor for a Vietnamese finalist, because there is no distribution to compare against. When there is no distribution, every judgement becomes a feeling, including the judgement of an expert.

In March 2026, the entire competition calendar stopped. I lost my job in a round of layoffs. Instead of waiting, I assembled 3,487 Bundesliga matches from 2026 to 2026 and set them against 412 matches played behind closed doors after the league returned. Home advantage fell 42 percent, from an average of 0.48 goals per match to 0.28. The study was published three days later, and my first consulting contract came out of it.

When the world stopped turning, I built my own rotation of data. Vietnamese swimming has an off-season of four to six months every year. That is enough time to rebuild a split database from video.

The cost is not in equipment. A national final has eight lanes. One fixed camera, one person marking checkpoints, four splits for eight swimmers. One person with one laptop can process a final in about forty minutes. The problem is that nobody is assigned the job.

There is one more point that rarely gets said. At some domestic meets, times are taken by hand. The error between two stopwatch operators is often larger than 0.1 seconds, and in many Vietnamese finals the gap between fourth and eighth place is smaller than that. Which means the colour of a medal in certain events is decided by measurement noise, not by who swam faster. I do not believe in luck; I believe in the margin of error. And here the margin of error is wider than the margin of victory.

The contrarian angle: a medal is a numerator without a denominator

The widespread belief in Vietnamese media: swimming is rising, and the proof is the medal count at recent SEA Games. It is a view with a foundation, and I will not belittle it by calling it sentiment. A medal is tangible and it has real value.

But a medal count is a numerator attached to an unpublished denominator. A gold medal in an event with six entrants is fundamentally different from a gold medal in an event with twenty-two. The printed result looks the same. The meaning does not.

Sports officials will say, reasonably, that the budget should go into pools and coaches, not into a timing system and a data analyst. Without water to train in, nobody swims fast. I agree with that premise.

What I disagree with is treating the two as mutually exclusive in the first year of a four-year cycle. The first year is when measurement is cheapest and leverage is highest, because the training plan can still be changed. Measuring an athlete in SEA Games year is an autopsy, not a diagnosis.

The "next Anh Vien" narrative also needs rereading. A miracle is only a data point that has not been regressed. Anh Vien was an extraordinary athlete, but the correct conclusion from her career is not "we produce champions." It is "we produced one." One point cannot draw a line. To speak about a system, you need a distribution.

What to track in the next cycle

The signal worth watching in the coming cycle is not medals. It is whether the national championship publishes split sheets, reaction times and entry counts by age group. If a public split file appears before the next SEA Games, that is a leading indicator worth more than any medal table. If it does not, we will have another season in which the results were recorded and the causes were forgotten. Numbers do not know how to lie, but the people reading them do. And data only dies when we stop asking questions.