The Risk Index is one of the metrics used in risk projects. Although the PSR is used to indicate the risk for a certain object, it is not an efficient metric if you want to compare objects, since the PSR calculation does not take into account the various objects that may have different numbers of controls, which may distort the results of a comparison.
To avoid this distortion, the Risk Index is used to compare objects, since this metric generates a relative number by analyzing the ratio of identified controls against the total of applicable controls for a certain object. Thus, the result of the Risk Index is a percentage – that is, a relative number that can be compared.
The basic formula to calculate the Risk Index for a certain object is: