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Triangulating a market size across three methods

Method · ~7 min read · public-methodology

A single market-size number is a single point of failure. If it came from one method, one wrong input moves the whole answer and nobody can tell. Triangulation fixes that by sizing the same market three independent ways and reporting not a point, but a central estimate and how much the methods disagreed — which is the most useful thing on the page.

The three legs

Each method anchors to a different public number, so agreement is real corroboration rather than the same assumption restated three times:

Detail on each lives in the top-down vs bottom-up and value-theory guides.

Why the median, not the average

Take the three warehouse-robotics estimates from the sample:

MethodTAM
Top-down$9.00B
Bottom-up$7.56B
Value-theory$10.80B

The median is $9.00B; the mean is $9.12B. Close here — but the median is chosen deliberately, because it resists one method running wild. If value-theory had come in at $30B instead of $10.8B (one bad input), the mean would jump to ~$15.5B while the median stays anchored at $9.00B. A single optimistic assumption should not be able to drag the headline number up, and the median guarantees it can't.

reported TAM = median(top-down, bottom-up, value-theory) = $9.00B

The spread becomes a confidence band

Disagreement is measured as a spread ratio, and mapped to a band the report presents honestly:

spread = (highest − lowest) ÷ median = ($10.80B − $7.56B) ÷ $9.00B = 36%tight
SpreadBandHow it's presented
≤ 40%tightMedian quoted as the headline — defensible
≤ 100%moderateA range, not a point; the method driving the high end is disclosed
> 100%wideNo single number quoted — an input needs a better source first

At 36% the sample lands tight, so the $9.00B median is reported as the headline. Had it come in at, say, 70%, the report would lead with a range and name whichever method drove the top of it — never a false-precision point.

The honest move: a wide spread is not a failure to hide — it's the report telling you the market genuinely isn't pin-downable yet from public data, and which input to go re-source. A number quoted despite a wide spread is the thing that blows up in a board room.
Honest caveat. Figures are the illustrative warehouse-robotics sample. On a real sector each of the three methods runs on its own dated public sources, and the band is computed from those, not these teaching numbers.

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The instant estimate runs all three methods, takes the median, and shows your tight / moderate / wide band live.

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