The final step in cost behavior analysis is to evaluate the profitability by region, which is a form of segment reporting. Segment reporting is the process of dividing your business into different segments, such as products, customers, or regions, and analyzing their performance separately. By doing so, you can identify the strengths and weaknesses of each segment and make better decisions. To evaluate profitability by region, you need to compare the contribution margin and the fixed costs of each region and calculate their segment margin, which is the difference between the contribution margin and the traceable fixed costs. Traceable fixed costs are those that can be directly attributed to a specific segment, such as regional advertising or rent. Segment margin represents the profit of each segment before deducting the common fixed costs, which are those that cannot be traced to a specific segment, such as corporate overhead or interest. By comparing the segment margins, you can determine which regions are more or less profitable and why.