M
mi06rasja
Hi
Iam trying to make my self independent from any statistical software program by making my own, using excel and macro. However, now Iam stuck trying to figure out how minitab construct their bell shape curve in there capability chart.
My assumption is that the formula for the bell shape cureve is the same as the formula for the normal distribution i.e.
f(x)=(1/sigma*sqrt(2*Pi))*e^(-(x-my)^2/2*sigma^2)
But in my case I use my own calculated sigma (within and overal). I also use Xbarbar as my my. At last I use diferent x values starting a couple of steps downstream from my Xbarbar and stops the same amount of steps higher from Xbarbar until f(x)=0,001.
However, when I make a chart using this procedure I do get a bell shape curve but this curve dosn't have the same width (deviation) as the one I compere with in minitab. My bell shape curve is really narrow and pointy in comparrison with minitab. What am I doing wrong?
Iam trying to make my self independent from any statistical software program by making my own, using excel and macro. However, now Iam stuck trying to figure out how minitab construct their bell shape curve in there capability chart.
My assumption is that the formula for the bell shape cureve is the same as the formula for the normal distribution i.e.
f(x)=(1/sigma*sqrt(2*Pi))*e^(-(x-my)^2/2*sigma^2)
But in my case I use my own calculated sigma (within and overal). I also use Xbarbar as my my. At last I use diferent x values starting a couple of steps downstream from my Xbarbar and stops the same amount of steps higher from Xbarbar until f(x)=0,001.
However, when I make a chart using this procedure I do get a bell shape curve but this curve dosn't have the same width (deviation) as the one I compere with in minitab. My bell shape curve is really narrow and pointy in comparrison with minitab. What am I doing wrong?