Inventory Planning

Inventory Forecasting Is Not a Math Problem

Sellers who keep stocking out don’t usually have a formula problem. They have a decision problem — and no amount of extra precision in the arithmetic will fix a constraint that lives somewhere else.

AmazeBase Podcast · 23 min Inventory & Cash Flow

A neat forecast in front of the cash and lead times that decide
Podcast episode 22 minutes 58 seconds

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Ask a seller who just ran out of stock what went wrong and you’ll usually hear a version of the same answer: the forecast was off. So they go looking for a better forecast — a smarter formula, more history, a tighter model.

Then it happens again.

This episode argues that the search for a better formula is usually the wrong search. Forecasting error is real, but for most sellers it isn’t the binding constraint. The binding constraint is the decision the forecast feeds into: how much cash is available, how long the lead time is, how much a stockout actually costs relative to the cost of holding too much, and how tolerable being wrong in each direction really is.

The through-line

A more accurate number changes nothing if the decision it feeds was never sensitive to accuracy in the first place. Find the constraint before you refine the arithmetic.


The written companion

This episode covers the same ground as one of the written pieces in this section, in conversational form. If you prefer to read the argument, or want it laid out step by step:

Once you accept the decision framing, the mechanics still matter. These three deal with them: