Where it starts
The white dot is today: the Hargraves' net worth as entered, . It is measured, not simulated, so the range has no width there. Every future opens from it.
The two bands and the line
Each year, the 1,000 futures are sorted from lowest to highest. The wide band holds the middle 80 of every 100: from the 10th percentile to the 90th. The narrow band holds the middle 50 of every 100. The line is the median: half the futures sit above it, half below.
The median is one future among the thousand, not a forecast. No future in the range is a promise.
Reading one year
Take a slice at Tom's 65. In 80 of 100 futures, the Hargraves' net worth sits between and . At Tom's 85, the same 80 run from to .
| Age | 10th percentile | Median | 90th percentile |
|---|
Across those twenty years, the low edge holds near the same figure while the high edge more than doubles. The width is the information: it says how far apart the futures have drifted.
Width, not the line
A range has two sources of width. One is what is not yet known about today: each fact not entered is a range of its own. The other is the time ahead, which widens the range every year. Entering a fact narrows the first; nothing narrows the second.
A chance is read off the same futures. It counts how many of the 1,000 reach a goal, and it carries a margin because 1,000 is a sample. The framework's page on probability sets out why.