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## Pooled mean and standard deviation

version 1.10.0.0 (1.53 KB) by R P

### R P (view profile)

Calculate pooled N, mean and STD (using, as inputs, subgroups N, mean and STD)

Updated 12 Aug 2014

Calculate pooled n, mean and std from n, mean and std of two groups
(to calculate it to N groups (N>2), repeat it N-1 times)
[npool,meanpool,stdpool] = pooledmeanstd(n1,mean1,std1,n2,mean2,std2)

Example:

n1=32;
sample1 = randi(100,n1,1);
mean1= mean(sample1);
std1= std(sample1);
n2=20;
sample2 = randi(100,n2,1);
mean2= mean(sample2);
std2= std(sample2);
n3=9;
sample3 = randi(100,n3,1);
mean3= mean(sample3);
std3= std(sample3);
pool_sample=[sample1;sample2;sample3];
meanpool_real= mean(pool_sample);
stdpool_real= std(pool_sample);

[npooltemp,meanpooltemp,stdpooltemp] = pooledmeanstd(n1,mean1,std1,n2,mean2,std2);
[npool_estimated,meanpool_estimated,stdpool_estimated] = pooledmeanstd(npooltemp,meanpooltemp,stdpooltemp,n3,mean3,std3);

disp(['meanpool_real=',num2str(meanpool_real),' meanpool_estimated=',num2str(meanpool_estimated)])
disp(['stdpool_real=',num2str(stdpool_real),' stdpool_estimated=',num2str(stdpool_estimated)])

### Cite As

R P (2020). Pooled mean and standard deviation (https://www.mathworks.com/matlabcentral/fileexchange/37233-pooled-mean-and-standard-deviation), MATLAB Central File Exchange. Retrieved .

Nathan Tomlin