Mellon Financial Corp. conducted a study on the costs of getting employees up-to-speed in new positions. Respondents, two-thirds of which were in Human Resources positions, were asked to estimate the time to full productivity for internal and external hires in eight standard job categories, including executives, managers, professionals, customer service representatives and more. Not surprisingly, the more complex the job, the longer the learning curve. Examining the learning curve length and shape yields number of unproductive days, which can be converted into lost revenue.