Fig. 1
From: Stepwise iterative maximum likelihood clustering approach
An illustration of stepwise iterative maximum likelihood method using a c = 2 cluster case. In this illustration, two clusters 
and 
are given with likelihood functions L1 and L2, respectively. The center of clusters are depicted by μ
1 and μ
2 (shown as ‘+’ inside two clusters). Initial total likelihood is Lold which is the sum of two likelihood functions (L1 + L2). A sample \( \mathrm{x}\in \)
is checked for grouping. It is advantageous to shift sample \( \mathrm{x} \) to cluster 
only if the new likelihood (Lnew = L
*1
+ L
*2
) is higher than the old likelihood; i.e., L
new
> L
old