---
title: Diagnose deviations in APM signals with Lookout
source: https://docs.newrelic.com/docs/apm/apm-ui-pages/monitoring/lookout-signals
---

Use [New Relic Lookout](https://docs.newrelic.com/docs/new-relic-solutions/new-relic-one/core-concepts/new-relic-lookout-monitor-your-estate-glance/) to detect deviations in your APM service entities' three golden signals (response time, error rate, and throughput) and analyze the behavior and causes of those deviations.

## How does it work?

On the **APM summary** page, Lookout compares the values of golden signals within the past five minutes against its values over the preceding hour. If Lookout detects a signifigant upward or downard trend in the signal, a **Diagnose** button appears on the corresponding APM summary chat.

![A screenshot of the Lookout diagnose button embedded within in APM Web transactions time chart.](https://docs.newrelic.com/images/embedded-lookout-diagnose-button.webp "Embedded Lookout diagnose button")

The Lookout **Diagnose** button embedded in an APM web transactions time chart

When clicked, the button opens a diagnostic Lookout tool which you can use to explore details about your golden signals.

![A screenshot of the Lookout diagnosis nerdlet launched from APM.](https://docs.newrelic.com/images/embedded-lookout-detail.webp "Embedded Lookout detail")

The Lookout diagnosis nerdlet launched from APM