The effectiveness of a privacy incident response process is best measured by its efficiency in handling and resolving incidents to mitigate harm. "Mean time to resolve" (MTTR) is a standard Key Performance Indicator (KPI) that directly quantifies the time taken from the detection of an incident to its complete resolution. A decreasing MTTR demonstrates that the response team and its processes are becoming more efficient and effective at containment, eradication, and recovery, which is the core function of incident response.

A. The decrease of security breaches measures the effectiveness of preventative security controls, not the reactive incident response process.

B. The decrease of notifiable breaches is an outcome that can be influenced by a good response, but it's not the most direct measure of the process's effectiveness itself.

C. The increase of privacy incidents reported by users indicates a strong reporting culture and user awareness, not the efficiency of the team responding to those reports.

1. Densmore

R. (2019). Privacy Program Management: Tools for Managing Privacy Within Your Organization (3rd ed.). IAPP. In Chapter 7

Section 7.5

"Metrics

" the text explains the importance of measuring the incident response function. It highlights time-based metrics such as "time to respond" and "time to remediate" as critical indicators of the program's effectiveness. A reduction in these times signifies an improvement in the response process.

2. National Institute of Standards and Technology (NIST). (2012). Computer Security Incident Handling Guide (Special Publication 800-61 Rev. 2). https://doi.org/10.6028/NIST.SP.800-61r2. Section 2.4.4

"Incident Handling Measures of Performance

" recommends metrics such as "Time from incident detection to incident recovery" to evaluate the performance and effectiveness of an incident response capability. This aligns directly with decreasing the mean time to resolve incidents.