Lean production should result in reduced inventories. If lean production is successfully implemented, the difference in net operating income computed under the absorption and variable costing methods should be reduced.

Lean production focuses on minimizing waste and increasing efficiency in production processes, which should lead to a reduction in inventories. This reduction in inventories should result in a smaller difference between net operating income computed under absorption and variable costing methods. This is because absorption costing includes fixed manufacturing overhead costs in the cost of goods sold, which can lead to higher inventory values and lower net operating income in periods of low sales. Variable costing, on the other hand, only includes variable manufacturing costs in the cost of goods sold, resulting in a more consistent net operating income regardless of inventory levels.