■ 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 year t to asset quality in yeart– 1. The AQIis an aggregate measure of the change in asset realization risk, which was suggested by Siegel. If