Signal, no signal, and anti-signal
Summarize
Summary of Signal, no signal, and anti-signal
The KPI Signals application in ServiceNow detects variations in KPI scores to help monitor workflow stability. It generates three types of indicators:
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- Signals: Indicate abnormal variations suggesting workflow changes or instability.
- Anti-signals: Indicate a long-term absence of abnormal variation, confirming workflow stability.
- No signal: Represents shorter periods with no detected abnormal variation, requiring no action or notification.
This functionality enables users to identify when to initiate process improvement efforts or maintain current operations based on statistical stability.
Key Features
- Signal Detection Criteria: KPI Signals identifies special cause variation based on three patterns:
- Outlier: Scores beyond three standard deviations (3-sigma) from the mean.
- Short run: Four consecutive scores on the same side of the mean with at least three close to the two standard deviation limit.
- Long run: Seven consecutive scores all above or below the mean.
- Breakdown Support: Signals can be detected for indicators with only one first-level breakdown element; multiple or second-level breakdowns are not supported.
- Anti-signal Generation: An anti-signal is issued when no signals have been detected for a period calculated as:
Baseline calculation period × Anti-signal factor.
By default, for daily indicators, this is 14 days × 2 = 28 days. - No Signal State: When no abnormal variation is detected for a shorter time than the anti-signal threshold, the application shows a "No signal" message without notifications or required actions.
- Dashboard Integration: KPI Signals-enabled indicators display insight cards on dashboards for quick visualization of signals and anti-signals.
What Customers Can Expect
- Timely alerts when KPI scores show statistically significant changes, enabling proactive process management.
- Confirmation of workflow stability through anti-signals, reducing unnecessary investigations.
- Clear differentiation between transient no signal periods and longer-term stability indicated by anti-signals.
- Out-of-the-box dashboard insights that help visualize signals and support data-driven decision making.
- Configurable parameters for baseline duration and anti-signal factor to tailor signal detection to specific business needs.
When KPI Signals detects abnormal variation in the scores of a KPI, it generates a signal. When KPI Signals does not detect abnormal variation for a significant amount of time, it generates an "anti-signal." The anti-signal lets you know that your workflow is under control.
- The presence of signals lets you know that a workflow has changed, or at least is not statistically stable.
- The long-term absence of signals indicates that a workflow is statistically stable. With this information you can decide to launch a process improvement initiative, for example.
Signals
- Outlier
- Every score beyond a three standard deviation (3-sigma) upper or lower limit.
- Short run
- Four consecutive scores on the same side of the central line, with three of the scores close to the upper or lower limit. "Close to the limit" is defined as outside two standard deviations.
- Long run
- Seven consecutive scores on the same side of the central line. That is, seven scores in a row all greater than or all less than the average value.
In the following example, you see a "Long run" signal: seven consecutive scores above or below the central line.
Anti-signals
Length of time to calculate the baseline for the KPI * Anti-signal factorThe application takes 14 days by default to calculate the baseline for a daily indicator. The default anti-signal factor is two. Thus, the default length of time to detect an anti-signal on a daily indicator is 28 days. For more information about setting the time to calculate a baseline, see Configure signal detection. For more information about setting the anti-signal factor, see Configure signal notifications.
In this example, the default configuration values apply to a daily indicator. The application has not detected a signal for 28 days, so it shows a 28-day anti-signal.
Although responsible users are notified when an anti-signal is generated, no action is required.
No signal
Usually no signal is detected for a shorter amount of time than it takes to detect an anti-signal. In this case, the application shows a simple "No signal" message. No notifications are sent and no action is necessary.
In the following example, no signal is detected for five days after the baseline was most recently reset. The baseline has been reset three times in the period being shown.