Abstract: Techniques for simulating content item selection events (CISEs) in a computer system are provided. For a first CISE, a first amount that a first content provider contributed as a result of being selected for the first CISE is determined. The first CISE is simulated by determining a second amount that a second content provider would have contributed as a result of the first CISE if the second content provider was selected for the first CISE instead of the first content provider. A second CISE is simulated in order to determine a difference between a third amount that a third content provider contributed as a result of being selected for the second CISE and a fourth amount that the third content provider would have contributed if the first content provider was not a candidate for selection in the second CISE. Based on the three amounts, an incremental value ratio for the first content provider is calculated.