Standard Deviation article.

[Ryridesmotox]

It appears to be good information, and may be helpful to people. As always, grains of salt.

RELOADERS CORNER: Standard Deviation

Before getting into improving bullet velocity Standard Deviation, it’s first necessary to understand what it is, and what it isn’t. KEEP READING Glen Zediker I got started on this topic last time, …

www.mssblog.com

 

[pbatesaz]

I look at SD and ES together. Knowing that in a normal distribution 95% of shots will fall within 2 SD of the mean (average), I take the SD and multiply by 4 to get the expected ES. If the observed ES is greater than that, I give more credence to the observed ES. If the observed ES is less than 4 times the SD, I go with the expected ES (4 times SD). Differences between the observed and expected ES are more likely to be seen with small shot samples. When you see a big discrepancy between expected and observed ES, think about obtaining a larger sample and remember that there is a 5% chance that the observed ES will be greater than 4X SD.