The entropy, drawn
Four ways of looking at the same radioactive decay. None of them is a summary statistic: they are the bytes themselves, arranged so that a flaw would be visible rather than reported.
These plots read the archive, which is the append-only record of bytes already emitted. They never draw on the fresh pool, because that refills at about 75 bytes a minute and spending it on a picture would starve the consumers it exists for. The instrument itself reports what it is doing right now.
The field
Bytes taken three at a time and read as coordinates. A biased source draws structure here: planes, lattices, a clump in one corner. A good one fills the cube with nothing to see, which is the least interesting picture a generator can produce and exactly the one it should.
bringing up the 3D field…
The return map
Each byte plotted against the one after it. Any rule connecting a value to its successor shows up as a shape. This is the plot that caught RANDU, whose output falls onto fifteen planes and looked fine by every other test of its day.
bringing up the return map…
The raster
One pixel per bit, in order. The eye is very good at finding periodicity, and a stream with any is hard to look at without seeing it.
bringing up the bit raster…
Phase space
This one plots the measurements rather than the bits themselves. Each point is one window of output placed by its own bias, entropy and serial correlation, so the cloud is the source describing itself over the last day rather than a single snapshot.
bringing up phase space…