how to find standard deviation in six sigma format?

I have plot my data with the help of scater plot. But in data statistics it is only mean and standard deviation. I need my plot which shows 1sigma, 2 sigma , 3sigma how to do that?

Answer 1

[Cris LaPierre]

The function std returns one standard deviation. Multiply by +/-1, +/-2 and +/-3 to get more than that.

Here's a simple example

% generate a distribution
x = linspace(425,745,200);
y = normpdf(x,580,35);

scatter(x,y)
mu = mean(x)

mu = 585

xline(mu,'g--')
sd = std(x)

sd = 93.0721

xline(mu + sd,'m--')
xline(mu - sd,'m--')
xline(mu + 2*sd,'b:')
xline(mu - 2*sd,'b:')
xline(mu + 3*sd,'k-.')
xline(mu - 3*sd,'k-.')

[SAKSHAM SHRIVASTAVA]

I want to plot a scatter curve with mean and sd by import an excel sheet. the code is as follows:

Corrected_UV_D4_spectra_1 = xlsread('corrected_uvd4_spectra_1','sheet1','A21:B341');

data = Corrected_UV_D4_spectra_1;

x = data(:,1);

y = data(:,2);

scatter(x,y)

mu = mean(x)

xline(mu,'g--')

sd = std(x)

xline(data_mean + data_std,'m--')

xline(data_mean - data_std,'m--')

xline(data_mean + 2*data_std,'b:')

xline(data_mean - 2*data_std,'b:')

xline(data_mean + 3*data_std,'k-.')

xline(data_mean - 3*data_std,'k-.')

But plot is now coming

after getting mean and sd in command window i got the error:

warning: Error

occurred while

executing the listener

callback for event

PostUpdate defined for

class

matlab.graphics.primitive.canvas.JavaCanvas:

Dot indexing is not

supported for

variables of this

type.

Error in bfitlisten

Error in bfitlisten

Error in bfitlisten

Error in bfitlisten

Error in bfitlisten

[Cris LaPierre]

I can't duplicate the error. Please attach your spreadsheet to your post using the paperclip icon