Methods and systems are directed to quantifying and prioritizing the impact of problems or changes in a computer system. Resources of a computer system are monitored by management tools. When a change occurs at a resource of a computer system or in log data generated by event sources of the computer system, one or more of the management tools generates an alert. The alert may be an alert that indicates a problem with the computer system resource or the alert may be an alert trigger identified in an event message of the log data. Methods described herein compute an impact factor that serves as a measure of the difference between event messages generated before the alert and event messages generated after the alert. The value of the impact factor associated with an alert may be used to quantitatively prioritize the alert and generate appropriate recommendations for responding to the alert.