As already discussed in the earlier chapters of this part of the book dealing with competitive strategies, business managers' interest in segment profitability has been increasing significantly in recent years. This can most easily be seen in the area of product profitability analysis. 'Product costing' has been a mainstay of cost and management accounting for many years, and many companies have developed very sophisticated cost apportionment systems. However, even for many of these financially sophisticated businesses, the concept of applying a decision-based analysis to relative product profitabilities is still new and is proving difficult for many managers to come to terms with.