
Run Chart Rules for Interpretation (2016) [pdf] - Tomte
http://www.qihub.scot.nhs.uk/media/529936/run%20chart%20rules.pdf
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titzer
From the very first paragraph,

> For example, for an event with two possible outcomes, where each outcome is
> likely to happen 50% of the time, the probability of the same outcome
> occurring six times in a row is less than 3 in 1000

This is wrong. The probability of, e.g. getting heads 6 times in a row is
1/2^6 which is 1/64\. The probability of getting 6 heads in a row or six tails
in a row is 1/2^5, which is 1/32.

~~~
jka
Strange. The document claims it's paraphrasing two sources, one of which is
linked[0] in the document itself.

The linked source does contain the diagram your quote is associated with, but
not the (agreed, questionable) commentary about probabilities.

[0] -
[http://www.knowledge.scot.nhs.uk/media/CLT/ResourceUploads/1...](http://www.knowledge.scot.nhs.uk/media/CLT/ResourceUploads/1006891/Good_Practice_Guide_Data_Management_run_chart_rules.pdf)

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DanBC
For a fuller discussion of statistical process control charts in the NHS (an
English NHS example this time) you might be interested in "Making Data Count".
[https://improvement.nhs.uk/resources/making-data-
count/](https://improvement.nhs.uk/resources/making-data-count/)

Especially the Plot the Dots booklet:
[https://improvement.nhs.uk/documents/2748/NHS_MAKING_DATA_CO...](https://improvement.nhs.uk/documents/2748/NHS_MAKING_DATA_COUNT_2019_FINAL.pdf)

