# Reply To: What is standard deviation?

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oldspook –

I’m glad you responded & you are right:). Standard deviation is a good predictive calculation that is intended to represent the total population of a * normal distribution*. Scotchmo’s string #2 is not a normal distribution – I suspect he knows this. However, it is a very clever & extreme example where standard deviation provided what appears to be better information versus ES.

As always, I need to be more clear in my writing. I prefer ES for a gun that I have verified has a normal distribution. Flyers will happen and influence ES – your point is accurate & conceded.

Now I’m no expert on the varying shot string characteristics of the PCP airgun world, but I do know (as most member do) MV is important for accuracy – especially as target distance increases. So, if one has a gun that shots a normal distribution & longer range accuracy is important, what statistical measure would you put more priority on?

Your answer may vary with regulated versus un-regulated airguns, but please think about it in terms of user refill pressure. What I mean is that most guys refill a PCP at some fixed air tube pressure. Looking forward to your response.

*. Scotchmo's string #2 is not a normal distribution - I suspect he knows this. However, it is a very clever & extreme example where standard deviation provided what appears to be better information versus ES. As always, I need to be more clear in my writing. I prefer ES for a gun that I have verified has a normal distribution. Flyers will happen and influence ES - your point is accurate & conceded. Now I'm no expert on the varying shot string characteristics of the PCP airgun world, but I do know (as most member do) MV is important for accuracy - especially as target distance increases. So, if one has a gun that shots a normal distribution & longer range accuracy is important, what statistical measure would you put more priority on? Your answer may vary with regulated versus un-regulated airguns, but please think about it in terms of user refill pressure. What I mean is that most guys refill a PCP at some fixed air tube pressure. Looking forward to your response.*

**normal distribution**