Here's the skinny on the most common methods of assessing ROI:
Quick calculators: These are fill-in-the-blank forms, often on the Web sites of tech companies. Potential customers plug in facts about their business and get a ballpark estimate of how much they can save. How useful: Because the formulas are so general, experts don't consider them to be reliable forecasts of savings.
Case studies: Tech outfits often trot out case studies of completed projects to try to persuade potential customers to buy their products. How useful: Problem is, each company's situation is different.
ROI forecasts: Detailed info about a company's technology and business performance is collected and compared with results from its peers. How useful: This is fairly reliable because it focuses on one company.
ROI assessments: These studies are done after a project is finished. How useful: The approach is highly accurate. But because it's done after the fact, it doesn't help with buying decisions.
Get BusinessWeek directly on your desktop with our RSS feeds.
Add BusinessWeek news to your Web site with our headline feed.
Click to buy an e-print or reprint of a BusinessWeek or BusinessWeek Online story or video.
To subscribe online to BusinessWeek magazine, please click here.