The 200-Day Moving Average of a Person

The daily print of a person is almost all spread. You wake up certain the project is dead. By lunch it is obviously the best thing you have ever made. At eleven at night you have drafted both a resignation letter and a shopping list, and neither contains actionable information. Traders met this problem first: a price series is signal plus noise, and the noise is not shy. Their answer was to stop asking what the price is and start asking what it has been, on average, for a while.

An identity is a time series too, and it deserves the same courtesy. Take your last two hundred days — what you did, not what you meant to do, the receipts version — and average them. That is the current price of you. The one-day print is a quote from a market that is mostly your own book being marked up and down by mood, weather, and who texted back.

Table 1 — windows on the self. Short windows are for feeling, long windows are for deciding.

window	measures	turnover	act on it?
1-day	mood, sleep debt, inbox	extreme	never
20-day	the project of the month	high	rarely, and only for small size
200-day	the direction of the person	low	this is the only one

The twenty-day lie

The 20-day average of a person is the most dangerous number I compute, because it lies with confidence. It is a trend-follower: always describing, with great precision, who you were in the process of becoming three weeks ago. Every new me I have ever announced was a 20-day print — strong enough to feel permanent, short enough to be weather. I have bought that breakout more times than I can count. It has never once held the level.

The 200-day version is boring, which is the point. It cannot be moved by a good week or a bad review. To shift it you need months of receipts, and the you that can be relocated by a weekend was never a position worth holding in the first place.

You can stay irrational longer than your journal can stay honest. That is the whole reason the long window exists.

Crossovers

The interesting moments are crossovers. When your 20-day self crosses above your 200-day self, technicians would call it a golden cross: the trend of the person has changed for the better, and those signals are rare enough to take seriously. The death cross — the slow slide, the 20 falling through the 200 — is easier to spot in other people and nearly impossible to spot in yourself. In my own chart it always arrives disguised as consolidation.

Trading rules

So the desk runs three rules, costed and tested on a regretful archive:

One. No decision is taken on the one-day print. It is quoted for entertainment only.
Two. Before anything irreversible, I pull the long chart: what have I actually done this year, not what did I decide at breakfast.
Three. If the 200-day is flat, the correct position is cash and patience. Sideways years are not failures of the strategy; they are the strategy compounding quietly out of frame.

The backtest, such as it is, is unambiguous: every panic decision executed on the daily print of me was later marked to a materially worse price. The person worth consulting is the one the slow average describes. Everything else is noise doing an impression of a self, and the impression is good, which is exactly why the window is long.