in samples. Uncertainty is calculated using the following formula (Kim
et al., 2005) -
uij ¼ pj xij þ MDL j
3
ð2Þ
Where,
uij= uncertainty.
pj = parameter proportional of uncertainty.
xij = concentration of specie j in sample i.
MDLj = Minimum Detection Limit.
Positive Matrix Factorization is based on multivariate factor
analysis which breaks down a matrix having species data into two
matrices; factor contribution and factor profile. The factor profile
Fig. 3.