How to find points 3 std away from the mean in vector

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Hello,
Could you please help me to find a way how to find the points which are 3 std away from the mean in vector?

Accepted Answer

Image Analyst
Image Analyst on 9 Sep 2014
Edited: Image Analyst on 9 Sep 2014
Assuming you really mean " more than 3 standard deviations away from the mean"...
% Get the mean and standard deviation of the vector
theMean = mean(yourVector);
stdDev = std(yourVector);
% Get a logical vector of the locations where the value is more than 3 sd away from the mean.
locationsAwayFromMean = abs(yourVector - theMean) > stdDev;
% Extract only those elements
outlierValues = yourVector(locationsAwayFromMean);
  4 Comments
Filippe Frulli
Filippe Frulli on 19 Aug 2020
Edited: Filippe Frulli on 19 Aug 2020
May I please ask how exactly is the 3*standard deviations calculated?
Based on my interpretation of Image Analyst's solution, I only see 1 standard deviation being calculated. I would really appreciate clarification.
Shouldn't it be
locationsAwayFromMean = abs(yourVector - theMean) > 3*stdDev?
Image Analyst
Image Analyst on 19 Aug 2020
Yes, sorry for the error and thanks for the clarification.

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