Mean Time to Respond (MTTR), often used interchangeably with Mean Time to Resolution, is the key performance indicator (KPI) that measures the average time taken to manage an incident from its initial alert to its final closure. In the context of Splunk Enterprise Security, this metric calculates the duration from the createtime of a notable event to its closetime. This precisely matches the scenario of measuring the time between alert creation and the event's closure, even if the resolution is to classify it as a false positive.

B. MTBF (Mean Time Between Failures): This is a reliability metric used to measure the average time between system or component failures, not for tracking incident response lifecycles.

C. MTTA (Mean Time to Acknowledge): This metric measures only the initial part of the response process: the time from alert creation until an analyst formally acknowledges or begins investigating it.

D. MTTD (Mean Time to Detect): This metric measures the time it takes to identify a potential incident before an alert is even created. It covers the period from the actual malicious activity to its discovery.

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1. Splunk Enterprise Security Documentation

Use Splunk Enterprise Security

"Key performance indicators for the SOC" section.

Reference Detail: This official documentation defines Mean Time to Resolution (MTTR) as "The average time it takes for your team to resolve a security threat." It specifies that the calculation for the duration of a notable event is closetime - createtime

which directly corresponds to the time between alert creation and the close of the event as described in the question.

2. Splunk Enterprise Security Documentation

Administer Splunk Enterprise Security

"Incident Review settings" section.

Reference Detail: This section discusses the configuration of notable event statuses

which are integral to the incident response workflow. The transition of a notable event from "New" to a terminal state like "Closed" is the basis for calculating MTTR. The time spent in this lifecycle is the core of the MTTR metric.

3. Splunk White Paper

The Essential Guide to Security

"Measuring and Communicating Your Security Program" chapter.

Reference Detail: In the section on "Security Operations Metrics

" this guide outlines key metrics for a SOC. It defines MTTR as the time from when an incident is declared (i.e.

an alert is created) to when it is resolved

reinforcing its use for measuring the entire response and resolution phase.