What price_eur_mwh actually contains in grid-energy-load

Working through grid-energy-load again. price_eur_mwh is the column people trip over, so here is what it actually looks like.

8,760 rows, no nulls, 4,568 distinct values. Day-ahead clearing price. Can be negative.

The five-number version: min -55.42, p10 26.38, median 47.77, p90 66.20, max 94.02. The mean is 46.87.

The p10 to p90 band — 26.38 to 66.20 — is where ordinary rows live, and it is the pair worth quoting when somebody asks what to expect. Min and max describe the two strangest rows in the table and nothing else; they are useful for spotting impossible values and misleading for everything else.

select
  count(*)                        as rows,
  count(price_eur_mwh)            as present,
  count(*) - count(price_eur_mwh) as nulls,
  count(distinct price_eur_mwh)   as distinct_values
from grid_energy_load;

Nothing dramatic: the mean and median are within 1.9% of each other, so an average is a fair summary. That is worth confirming rather than assuming — it is not true of most money columns.

Where this matters: a symmetric column is one you can average, threshold and chart without hedging, which makes it unusually cheap to work with. Knowing which of your columns are like this and which are not is most of knowing when to be careful.

The grain is one row per hour, which is the context every one of those numbers depends on. None of them survive a change of grain, which is why "profile the column" and "profile the table" are the same job. Full schema, and the CSV, on the dataset page.