SoFi offers an automatic error matrix calculation for data imported from .xls and .xlsx files. It is assumed that the PMF input from .itx files comes already with an error matrix.
If the field for the error matrix is left blank, so SoFi assumes that there is no error matrix and gives the option to let the error matrix (later named “Error_Mx_SoFi”) be calculated automatically. SoFi supports two types of error matrix calculation:
- “Polissar et al., 1998”: data matrix and error matrix are composed as fixed fractions of the method detection limit (MDL)
- “Norris et al., 2014” Equation‐based uncertainty and an error fraction for concentrations above the MDL. For concentrations below the MDL, the approach from Polissar et al. (1998) is followed.
Both error matrix calculations require the input of the method detection limit (MDL) for each element/species/ion/etc. The equation‐based uncertainty additionally requires the input of the error fraction. SoFi accepts an error
fraction for each element or one error fraction for all elements. Both, input values and error fraction need to be separated be semicolons.