Lex Luthor: a quarter of the offer at one price

This article is the counterpoint to a previous one, and it must be said from the outset to avoid a misunderstanding. I have shown elsewhere that an isolated ad at €615 could overturn an average without touching the median, and I drew a recommendation from this: prefer the median. This recommendation remains correct, but it is incomplete, and the reading reviewed here shows exactly where it stops.

A median is resistant to extreme values ​​because it only has ranks, not amounts. This is his strength. This is also its weakness: it is entirely governed by the number of advertisements, and therefore by a seller who publishes many at once.

A block of seventy ads

The corpus: 288 distinct lines, obtained by crossing three queries from the French market on August 30, 2026 and removing duplicates. Each amount is what a sellerhoped to getat this moment. Nothing changed hands before my eyes, and a single photo says nothing of a movement: it photographs an offer.

Fifty-seven percent of these ads display an amount in whole euros, without cents. This is already a lot, and it indicates that the market does not think here in psychological prices: only 5% of the advertisements end with ninety-nine cents. But the salient fact is elsewhere.

Exactly seventy ads display €4.00. It is not an approximate convergence around an order of magnitude: it is the same value to the cent, repeated seventy times. Examining these lines, sixty-three of them turn out to be numbers from a single series, from 687 to 885, from what is clearly a single seller selling a long line at a flat rate.

This last point deserves to be formulated clearly, because it is the heart of the problem. A flat rate is a commercial decision: the seller chooses not to differentiate his copies. This is perfectly legitimate, and often rational — sorting two hundred issues one by one costs more than the expected profit. But this means that these seventy prices do not carry any information on the booklets concerned. They provide information on a seller's policy, and nothing else.

How to recognize a single price block

The sign is simple and can be identified without tools: a value which returns many times to the nearest cent. An ordinary market produces dispersed prices, even when they concentrate around an order of magnitude; you can find €3.90, €4.20, €4.50. Seventy times exactly €4.00, this does not happen by chance.

The second clue is the nature of the lines concerned. If they belong to the same series and cover a continuous range of numbers, the conclusion is clear: it is a single stock put online at once. In this case, one hundred and ninety-eight rows separate the first number from the last, without any being distinguished by its price.

A third, more discreet index concerns quantiles. When the tenth percentile and the twenty-fifth percentile display the same value, a single amount occupies this entire interval. This is a reliable signal, and it appears when we look at the quantiles rather than just the bounds — which is good practice anyway.

A fourth clue, less immediate, relates to the general form of the prices recorded. Fifty-seven percent of the amounts are whole euros, and only 5% end in ninety-nine cents. This scarcity of psychological prices says something about the observed market: we do not find brands optimizing their display, but individuals who round up. A rounding market naturally produces concentrations on simple values ​​— four euros, five euros, ten euros — and these concentrations are not single seller blocks.

We must therefore distinguish two phenomena which are similar at first glance. Soft concentration, where several independent sellers converge on a round value, is real information: it indicates a shared order of magnitude. The rigid block, where a single hand aligns dozens of lines to the nearest cent over a continuous range of numbers, is not one of them. The statement examined here contains both: fourteen ads at ten euros, fourteen at five euros, eleven at six euros — then seventy at four euros.

The ratio between these numbers is what allows us to decide. Going from fourteen to seventy is not a change in intensity: it is a change in nature. A spontaneous convergence between independent sellers does not produce a workforce five times greater than its immediate neighbors on a value which is nothing more remarkable than the others.

Six practical consequences

What this statement does not establish

It does not establish that this price is too low or too high. A flat rate may be generous for some issues and harsh for others, and I have no way of judging this issue by issue. What the reading shows is that this price does not vary - therefore it does not measure any difference.

Nor does it formally prove that these sixty-three lines come from a single seller. I deduce this from the continuity of the range of numbers, the strict identity of the amount and the resemblance of the wording. This is a reasonable inference, not a direct observation, and it could be wrong: nothing prevents two sellers from adopting the same package on the same series.

Finally, this case says nothing about the frequency of the process on the market in general. A block of this size in a survey of 288 advertisements is a notable fact; I don't know if it's common. This is all the more reason to look at the distribution of each reading rather than applying a rule learned elsewhere.

Translate this into a file

The instruction:before using a median as a benchmark, count how many distinct announcements actually meet it.Seventy lines at the same price count as seventy in the calculation and only one in the information. The difference between these two numbers is what separates a usable benchmark from a misleading number.

In practice, note in your observations not only the median and the number of announcements, but also the most frequent amount and its number. These two additional pieces of information fit into a few characters and are enough to spot a block months later, when you have forgotten the details of the statement.

When you detect a block, the best practice is to calculate your benchmark without it, and keep the two values, specifying which ones. Here, that would give: median of €7.27 out of 288 ads, or €10.03 out of 218 after removing a flat rate. Both are true, they just answer two different questions.

There remains one case where the block is exactly what you are interested in: the one where you are looking for precisely a number in that range. A seller who sells two hundred issues at the single price is then an opportunity, not a bias. The same observation changes meaning depending on what we expect from it — which is why it is better to note it than to summarize it.