# Adding outlier to a matrix

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Niki on 22 May 2014
Commented: Star Strider on 22 May 2014
Hi , I have a matrix of intensities (n*p). I want to add an outlier to it. Do you have any idea about how to simulate an outlier? I was thinking to take the mean of matrix and then multiply it to some very high value?
Do you have any idea ?

Star Strider on 22 May 2014
I suggest:
M = rand(4,5); % Create data
Msts = [mean(M(:)) std(M(:))];
Outlier = Msts(1)+5*Msts(2);
Define the outlier by a multiple of the standard deviation from the mean. An value of 5*std is quite far out.
Star Strider on 22 May 2014
My pleasure, and thanks!

Roger Wohlwend on 22 May 2014
Actually you answered your question yourself. Instead of the mean I would use the maximum value of the matrix. Multiply that number by a certain value. That's all. It is quite easy.
Niki on 22 May 2014
In fact, I want to know whether it is scientifically correct or not? It is not a number. As I explained it is a matrix of n*p so I wont have a value as outlier but a row which corresponds as an outlier
On the other hand, do you know any way to show it as a outlier ?