Calculate 2 standard deviations
35 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
I am trying to calculate +/- two standard deviations from the mean of a bunch of values. I am not sure if I am using the standard deviation function properly. Would I just multiply by two to get 2 standard deviations?
dmean = mean(values(:,1)); upperstd = dmean+2*std(values(:,1)); lowerstd = dmean-2*std(values(:,1));
0 commentaires
Réponse acceptée
Wayne King
le 28 Août 2011
Hi Chris, for a matrix of data
x = randn(10,4);
mean(x)+2*std(x)
mean(x)-2*std(x)
gives the sample means of the columns plus/minus 2 times the standard deviation. The question is whether you really want the sample standard deviation here, or the standard error of the mean.
Wayne
2 commentaires
jay yawson
le 17 Juin 2019
Hello Wayne King. In this case, how would you calculate the standard error of the mean?
Thomas To
le 20 Jan 2020
Jay, the standard error is calculated by taking the standard deviation and dividing it by the square root of N-th samples used to calculate the standard deviation. ![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/262737/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/262737/image.png)
Plus de réponses (1)
Voir également
Catégories
En savoir plus sur Signal Processing Toolbox dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!