Storage crisis tracker - how bad are prices right now?

What the index does and does not tell you

Each line is a matched-basket price index. For every pair of consecutive days we take every listing we priced on both days, work out how much each one's own price moved, and take the geometric average of those moves. Those daily steps are chained together and set to 100 on the baseline date. The three lines share that date, which is what makes them comparable to one another rather than three sets of dollar figures with wildly different magnitudes on one axis.

The reason for that method rather than simply charting the median of everything in stock is worth being blunt about, because we got it wrong first. A median moves when prices move, and it also moves when the mix of tracked products moves. When we added thirty expensive NAS drives to the catalogue in a single week, the raw hard drive median jumped 53% without a single seller changing a single price. A matched basket cannot do that: a product that was not priced yesterday contributes nothing to today's step.

What the index still cannot tell you is what you will pay. It measures the direction the drives we already track have moved, not the level of the market. For the level, read the cheapest and median figures on the category pages, which are plain observations of what was actually on sale that day. An index at 130 and a genuinely good deal can coexist, and frequently do.

One more limit worth stating plainly. This is one retailer, Amazon US, tracked through its own API. It is a large and liquid market and it is not the whole market. Distributor and direct enterprise pricing move differently, and a reader buying pallets will not see these numbers.

Citing this page

Quote a figure, link to the page, and tell readers where the number came from. That is ordinary citation and it needs no permission from us.

We do not offer this as an open dataset, and we removed an earlier notice that did. The underlying prices are retrieved under a licence that does not permit us to pass redistribution rights on to anyone else, so bulk reuse, republication of the series, or building a product on top of these numbers is something to ask about first rather than something we can grant in a footer. The contact page reaches us, and we would rather have the conversation than have you rely on a permission we cannot give.