StdDev "it's not a component, it describes the Bell curve."
Not true
Here is an equation for a Bell curve.
f(x)=y=[1/(S*sqrt(2Pi)]*e^[-0.5*[(x-u)/S]^2]
Where
u=mean (constant, calculated), locates the center
S=StdDev (constant,calculated), determines dispersion
e=2.7183 (constant...