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

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?

Answer 1

[Image Analyst]

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);

[Image Analyst]

Olga's "Answer" moved here:

Thanks a lot! And how can i delete these outlierValues from myVector?

[Image Analyst]

yourVector(locationsAwayFromMean) = []; % Remove/delete outlier locations.

[Filippe Frulli]

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]

Yes, sorry for the error and thanks for the clarification.