8

A block is generated every 10 minutes, on average. What is the standard deviation of this distribution?

It seems to be a measurable property, not a calculable one.

Is there a chart of the standard dev over time somewhere (should be added to blockchain.info)?

  • Why do you ask about s.e. only versus robust statistics like quantiles? – alancalvitti May 21 '15 at 4:34
11

Excluding complications like difficulty changes and temporary blockchain splits, you can model the block generation time as an exponential distribution.

An exponential distribution has a standard deviation equal to the expectancy value. This predicts a 10 minute standard deviation for Bitcoin.


Measuring the actual distribution isn't that easy. While each block contains a timestamp, that timestamp isn't very accurate, and sometimes the time difference between blocks is even negative.
The timestamp doesn't change over the course of a single share, and some miners deliberately use timestamps deviating from the actual time

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