Crucial to any training course or learning 'intervention' is ROI, return on investment. This is usually measured by the impact on the business bottom line, i.e. an increase in revenue or productivity because of the training, but often this is difficult to measure. Since the crash of 2007/8, HR and training departments have often found they are required to do more with less as budgets are slashed, and so ROI is paramount for any organised activity. ROI represents the fourth level of the Kirkpatrick evaluation model, although some would dispute that ROI is in fact a fifth required level to the current model.