A research analyst is trying to determine whether a firm's price-earnings (PE) and price-sales (PS) ratios can explain the firm's stock performance over the past year. A PE ratio is calculated as a firm's share price compared to the income or profit earned by the firm per share. Generally, a high PE ratio suggests that investors are expecting higher earnings growth in the future compared to companies with a lower PE ratio. The PS ratio is calculated by dividing a firm's share price by the firm's revenue per share for the trailing 12 months. In short, investors can use the PS ratio to determine how much they are paying for a dollar of the firm's sales rather than a dollar of its earnings (PE ratio). In general, the lower the PS ratio, the more attractive the investment. The accompanying table shows a portion of the year-to-date returns (Return in %) and the PE and PS ratios for 30 firms. Firm Return PE PS 1 4.4 14.35 2.39 2 -4.5 11.00 0.81 1 4 30 16.3 13.97 1.96 Click here for the Excel Data File a-1. Estimate: Return - Be + BPE + B2PS +. (Negative values should be indicated by a minus sign. Round your answers to 2 decimal places.) Predicted Return= PE+ PS a-2. Are the signs on the coefficients as expected? Yes No