stderr

function stde=stderr(x,dim)

 Returns an estimate of the standard error of the mean of x (i.e. the 
 estimated standard deviation divided by the square root of the number of 
 observations)

 Required Input:
   x - A vector or matrix of data
 
 Optional Input:
   dim - The dimension of x that corresponds to observations.  For example, 
   the EEGLAB EEG.data matrix has dimenstions electrode x time point x
   observation, so dim would be 3. {default: 1}

0001 function stde=stderr(x,dim)
0002 %function stde=stderr(x,dim)
0003 %
0004 % Returns an estimate of the standard error of the mean of x (i.e. the
0005 % estimated standard deviation divided by the square root of the number of
0006 % observations)
0007 %
0008 % Required Input:
0009 %   x - A vector or matrix of data
0010 %
0011 % Optional Input:
0012 %   dim - The dimension of x that corresponds to observations.  For example,
0013 %   the EEGLAB EEG.data matrix has dimenstions electrode x time point x
0014 %   observation, so dim would be 3. {default: 1}
0015 
0016 if nargin<2,
0017    dim=1; 
0018 end
0019 
0020 mx_dim=length(size(x));
0021 if dim>mx_dim,
0022    error('x has only %d dimensions but argument dim equals %d.',mx_dim,dim); 
0023 end
0024 
0025 n_obs=size(x,dim);
0026 if n_obs==1,
0027   error('x needs to have more than one element in dimension %d (i.e., the dimension that contains multiple observations)',dim);
0028 end
0029 
0030 stde=squeeze(std(x,0,dim))/sqrt(n_obs);