■ Gross margin index. The GMIis the ratio of the gross margin in yeart– 1 to the gross margin in yeart. When the GMIis greater than 1, gross mar-gins have deteriorated. Lev and Thiagarajan suggested that deterioration of gross margin is anegative signal about a company’s prospects. So, if companies with poorer prospects are more likely to engage in earnings manipulation, I expected a positive relationship between GMIand the probability of earnings manipulation.10
■ Asset quality index. Asset quality in a given year is the ratio of noncurrent assets other than property, plant, and equipment (PP&E) to total assets and measures the proportion of total assets for which future benefits are potentially less certain. The asset quality index (AQI) is the ratio of asset quality in yeartto asset quality in yeart– 1. The AQIis an aggregate measure of the change in asset realization risk, which was suggested by Siegel. If