where: X1 ¼working capital/total assets; X2 ¼retained earnings/total assets; X3 ¼EBIT/total assets; X4 ¼market
value of equity/total debt; X5 ¼sales/total assets.
On the basis of this function Altman classifies 31 of the bankrupt firms and 32 of the ongoing firms correctly.2
The higher the Z-score of a firm, the lower its risk of bankruptcy. Although the estimated coefficients are sample
specific, this classic formula is considered to be robust and is still used by practitioners and researchers.
In subsequent years several derivatives of the classical Altman Z-score evolved. To apply it to non-listed firms
the suggestion was to measure X4 with the book value of equity as a proxy (Altman 2000). Based on Altman’s
original sample it followed model Z0: