# mean value and tandard deviation

Sir,

when i open a chart with Acceptance chart with X bar/S

Two chart was displaying one for mean value and another one is standard deviation

what is the difference between the mean value and tandard deviation

How the system calculating both value(mean value and tandard deviation )

Faisal

##### Sujit Gujar replied

Refer

actually Std deviation is calculated with the help of mean value " X bar "

check out

http://www.gcseguide.co.uk/standard_deviation.htm

Also refer

http://www.dspguide.com/ch2/2.htm