Arthur D. Little and other information systems consultants tell clients to develop custom software only if it provides a significant competitive advantage. For example, there is usually no measurable benefit to having a custom-written payroll or accounts receivable system. On the other hand, there may be significant benefits to sophisticated, just-in-time inventory management, product manufacturing software, or software for other core corporate functions. If a software application will not provide a competitive advantage, little advises its clients to buy software from an outside supplier. As a result, spending on in-house software development has plunged by up to two-thirds in recent years, while spending on software packages has more than doubled.