MATLAB: How to insert the mean in a plot

meanstandard deviationvariance

In this plot I want to insert the mean, the variance and standard deviation of this signal. Is there a particular function or a toolbox that executes it?

Best Answer

If you signal data is in vector y, say, then

ymean = mean(y);
ystddev = std(y);
yhi = ymean+ystdev;
ylo = ymean-ystdev;
xrange = [0 60]; % or whatever you want
plot(xrange, [ymean ymean],xrange,[ylo ylo], xrange, [yhi yhi])

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MATLAB: How to plot outliers from mean

There are three steps:

Create an algorithm to define the outliers
Identify the points that meet that definition
Plot those points

Here is an example. You'll need to adapt to your case, for example, by doing this calculation inside of each for loop, and using your own definition of what constitutes an outlier.

Also, I would recommend against using red circles to identify outliers, since your plot is a red line.

% Make up some data
N = 1000;
y = randn(N,1);
y_mean = mean(y);
y_std = std(y);
% Define "outlier" as greater than 2 standard deviations away from the
% mean.
% Find the index to those points
outlierIndex = find(abs(y - y_mean) > 2*y_std);
figure
hold on
% Plot the data
plot(y,'.')
% Plot a red circle around the outliers
plot(outlierIndex,y(outlierIndex),'ro')

MATLAB: Standard deviation in errorbar

Not silly at all, however it may not produce the result you want.

It might be more appropriate to calculate the errors as the standard error of the mean (S.E.M.)

err = 2*(std(y,[],2)/sqrt(size(y,2)));                  % 2 x Standard Error Of The Mean

then:

figure
errorbar(x, mean(y,2), err) % 2 standard errors of the mean

rather than the standard deviation of the observations themselves.

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Related Solutions

MATLAB: How to plot outliers from mean

MATLAB: Standard deviation in errorbar

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