From 98c0d1ab3c3bf43bc85725b79fc5f0ff6f572da1 Mon Sep 17 00:00:00 2001 From: ReaperOfVeriod Date: Sun, 11 Oct 2026 03:34:24 +0200 Subject: [PATCH] Re-verify the 368 stride with a control matched to its data The sky autocorrelation turned out to be inflated by a control that did not match the data, so the 368 result was re-checked the same way rather than being left on the evidence I now know to be weak. Range measured: each level's post-shrub region start, first 65536 bytes. Method: as before, but the control is the same bytes shuffled rather than uniform random. Shuffling preserves the value distribution and destroys only the ordering, which is what a control for this statistic needs to do. Level 0's region is evenly distributed -- 256 distinct byte values, most common only 15.6% -- so uniform random was the appropriate control here, and the shuffled control independently confirms it, reading 0.0000 at strides 340, 368 and 4 against the real data's 0.1110 at 368. Recomputed across all levels with matched controls: 24 of 24 peak at exactly 368, every one with excess above 0.05. So the 368 period stands, now with a control appropriate to its data. The contrast is the useful part: the same statistic, asked the same question of two regions, gave a real answer in one and an inflated one in the other, and the only thing that separated them was whether the control matched the byte distribution. --- docs/formats/core-data-regions.md | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/docs/formats/core-data-regions.md b/docs/formats/core-data-regions.md index 6a656f8..2a2d526 100644 --- a/docs/formats/core-data-regions.md +++ b/docs/formats/core-data-regions.md @@ -292,3 +292,30 @@ do not: an earlier "256x236" is wrong and should not be used. So the sky region is not one thing. Its first ~60 KB is an image; the rest is whatever the layer offsets address. Both halves still need work, and the image is the tractable one. + +## Re-verified: the 368 stride, against a matched control + +The sky autocorrelation was found to be inflated by a control that did not +match the data, so the 368 result was re-checked the same way. + +**Range measured:** each level's post-shrub region start, first 65,536 bytes. + +**Method:** as before, but the control is the same bytes shuffled rather than +uniform random bytes. Shuffling preserves the value distribution and destroys +only the ordering, which is exactly what the control needs to do. + +**Result:** + +- Level 0's region is evenly distributed: 256 distinct byte values, most + common only 15.6%. Uniform random was therefore the *appropriate* control + here, and the shuffled control independently confirms it, reading **0.0000** + at strides 340, 368 and 4. +- Level 0 peak remains 368 at 0.1110, against 0.0000 for the matched control. +- Recomputed across all levels with matched controls: **24 of 24 peak at + exactly 368, every one with excess above 0.05.** + +So the 368-byte period stands, now with a control appropriate to its data. +The contrast with sky is the point: the same statistic on the same kind of +question gave a real answer in one region and an inflated one in the other, +and the only thing that told them apart was whether the control matched the +byte distribution.