Standard Deviation
 

Does anyone understand SD well enough to explain how the hell I use it?

IE) I have a mean of 100 (baseline) and need to find the control limits for the graph in +-2 with an SD of 4.


#
#--------------------------------------------NEED
102
101
100-----------------BASE------------------
99
98
#--------------------------------------------NEED
#

:confused:

fuk if I know bro. Steve will probably figure it out.... or BDC

ehhh pain in the ass work. im clueless too

actually....i know it kinda. im actually studying some shit for econometrics and aggregate analysis right not involving that, i'll see if i can write something that makes sence sometime tonight

they way i just learned is that the control limits are either set by the instructor or are +/- 2.66times(average of the moving ranges) and "moving range" being the absolute value of the difference between two consecutive data points plotted in the trend chart.

then there's some other control limits that are for ideal cases(which i think is yours)that are +/- (#ofS.D.'s), which i think is what you need. so put all your data in an excel spread sheet make it tell you the standard deviation and I think your control limits would be +/-(4 times whatever# excel gives you).

i could be wrong but i dont think i am.

Haha. I appreciate the vote of confidence Arnel, but I'll be fucked if I can do any sort of math that's even remotely complicated.

Got it!
SD x (the + value) --> + the mean
(4 x 2 = 8 + 100 = 108,92)

oh the standard deviation IS 4, i thought you had to find control points for a 4sigma(S.D.) system. never mind :od

yeah im doing something a bit different with SD.. i wouldnt have been able to help too much.