chrony terminology
Hi all,
The term “spread” on my print out refers to the difference between min and max fps and its expressed as fps.
Is “extreme spread” the same thing?
What’s “standard deviation” and how is it calculated?
For spread what are good numbers and what are poor? For example is a 100fps spread on a 40 shot string good, average or poor?
Same question for standard deviation.
Thanks in advance
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1) Basically yes to your first question, but depends on the sentence and how it’s used in. :rofl: Happy 4th !
2) Standard Deviation (a statistical function used in upper level Mathematics) is a measure of how close each shot’s velocity will be to the “average” shot. It is called STANDARD because it is computed in such a way that it has a standard meaning when compared to the NORMAL CURVE.
Average (Mean) Velocity (-Av-)
where V is velocity and n is the number of shots.
Standard Deviation, population, (-Sd-)
Since Standard Deviation is the most important information your chronograph can give you, it is useful to understand the reason for this. At least ten (10) shots are required to obtain a reliable average and Standard Deviation. Fewer shots (such as 3 or 5) are typically “small samples”, and are considered unreliable when measuring anything variable.
Except for the square root (I’m not in the mood for Calculus) I’ll manually expand/solve the Equation/Function above on paper in steps if you supply a 10 shot string.
3) I’m assuming you’re taking about a Condor ? ……… if so, poor.
4) Standard deviation for a Condor would be 8-10 fps would be very good/average, but it depends on a lot of factors ….. in theory the less the better.
~ Greg