ROA is calculated as Net Income by the average of Total assets over the past two periods. If the denominator is negative, then the field value will be empty. For quarterly ROA, the calculations take the LTM value of Net income.
Net income / Total average assets
It gives an idea of how efficiently a company’s assets are used to make a profit. A high ROA indicates that a company successfully converts invested money into income. It may vary markedly depending on the industry.