Which of the following ratios is NOT included as a parameter in Altman’s Z-Score model for predicting corporate bankruptcy?

The original Z-score formula was as follows: Z=1.2X1+ 1.4X2 + 3.3X3 + 0.6X4 + 1.0X5. • X1 = working capital / total assets. Measures liquid assets in relation to the size of the company. • X2 = retained earnings / total assets. Measures profitability that reflects the company's age and earning power. • X3 = earnings before interest and taxes / total assets. Measures operating efficiency art from tax and leveraging factors. It recognizes operating earnings as being important to long-term viability. • X4 = market value of equity/book e of total liabilities. Adds market dimension that can show up security price fluctuation as a possible red flag. • X5 = sales / total assets. The standard measure for total asset turnover (varies greatly from industry to industry).