How Big Was the 777x Miss?

Ada re-derives this chapter’s own numbers step by step, at full precision

ADA · CALCULATION AUDIT

How Big Was the 777x Miss?

In the early 1980s AT&T asked McKinsey to forecast the year-2000 mobile phone market, and the answer came back at 900,000 units. The actual number topped 700 million. The chapter calls the miss “about 777x” in one place and “nearly 1,000x” in another, which reads like a contradiction — so this audit re-runs the ratio to ask exactly how big the miss was, and whether those two figures really disagree.

Companion to the chapter IoT History — every number here comes from that chapter.

Ada: The chapter says McKinsey’s 1983 forecast of 900,000 mobile phones missed the year-2000 reality of 700 million by “about 777x” in one place and “1,000x” in another. Those are not a contradiction — they are the same miss rounded at two different scales. Let me show it.

Given a prediction of 900,000 units and an actual of 700,000,000 units:

• As a plain ratio: 700,000,000 / 900,000 = 777.78, so the actual market was about 778 times the forecast.
• As an underestimate factor, comparing the shortfall to the forecast: (700,000,000 - 900,000) / 900,000 = 699,100,000 / 900,000 = 776.78, which the chapter rounds to 777.

The precise figure is about 777x and the headline “1,000x” is simply its order-of-magnitude rounding — and for forecasting the lesson survives either rounding: a linear estimate anchored to a $4,000 handset missed an exponential adoption curve by nearly three orders of magnitude, so a paradigm-shift forecast must be judged on its growth model, not on its decimal places.

Every number above is taken from the chapter’s own material and re-derived step by step.