K
krichmond0306
I should know the answer to this off the top of my head but I am lost right now and need an explanation.
I have a data set n=218, Mean=1.6927 anf StDev=3.0210. To me this means that 95% of my data lies within the interval 0 and 7.7347 (mean+2*Stdev), a quick count confirms this. Yet a Minitab control chart gives me an UCL equal to Mean+2.33*(StdDev/2)=5.98.
Why? I know I should understand this but I think I am over thinking it.
I have a data set n=218, Mean=1.6927 anf StDev=3.0210. To me this means that 95% of my data lies within the interval 0 and 7.7347 (mean+2*Stdev), a quick count confirms this. Yet a Minitab control chart gives me an UCL equal to Mean+2.33*(StdDev/2)=5.98.
Why? I know I should understand this but I think I am over thinking it.