Fixed-size window evolving factor analysis FSWEFA

2 Fixed-size window evolving factor analysis (FSWEFA) 

When the rows of a data matrix follow a certain pattern, e.g. the appearance and disappearance of compounds as a function of time, a fixed-size window EFA is applicable. This is the case, for instance, for data sets generated by hyphenated measurement techniques such as HPLC with DAD. Fixed-size window EFA [22] can be applied for detecting the presence of minor compounds ( 1 %) and for the resolution of a data set into its components (pure spectra and elution profiles). 

Eigenstructure tracking (ETA), developed by Toft and Kvalheim [23] is very similar to FSWEFA. Here, one starts initially with a window of size 2 and the size is increased by one until a singular value representing noise is obtained, i.e. the window size is one higher than the number of co-eluting compounds. 

---