Examine Metric Trends

On this page

The Metric page provides a detailed view of a single metric across your Synthetic tests, helpful for diagnosing a specific issue or tracking a trend over time.

To view, navigate to Site → Synthetic → Web Vitals and choose LCP, CLS or TBT. Every other metric is reachable from Pulse: click the metric name above any chart.

The Synthetic Metric page for Largest Contentful Paint set to All pages, showing a median of 6.53 seconds rated Poor, a trend line per Test Profile, and panels breaking the metric down by Test Profile and by Deployment.

The Metric page opens on a median of every page in the Site, with a coloured line for each Test Profile.

Read the summary#

With the page selector set to All pages, the report covers your whole site:

  • Value: a median of every page tested, for the selected period.
  • Rating: a badge showing whether the value is good, needs improvement or poor. See Core Web Vitals thresholds for the values.
  • Chart: one coloured line per Test Profile, so you can see which testing conditions need the most work.

If you track Deploys, the chart also carries a marker for each release.

Metric by segment#

Beneath the chart, three panels break the aggregate apart:

  • By Test Profile: the metric for each Test Profile, to compare test conditions such as mobile on a slow connection against desktop on cable.
  • By Deployment: the metric for each of your recent releases.
  • By Page: the metric for each page tested in the Site, to tell whether a change is site-wide or isolated. Use the All pages link to open the full list.

Every row lists the value for the previous period, the percentage change, and the value for the selected period. Measurements are colour-coded, so you will know if a given area needs more work:

  • Green: Good
  • Yellow: Needs improvement
  • Red: Poor
The LCP by Deployment panel listing five releases with their revision, sample count, percentage change and metric value, one marked Collecting, alongside the LCP by Test Profile and LCP by Page panels.

Segmenting by deployment attributes a change in the metric to the release that caused it.

Compare releases#

The By Deployment panel lists your recent Deploys, each with:

  • Deployment: how long ago the release happened and its revision, linking out to the commit.
  • Samples: the number of tests collected since. A release still being tested is marked Collecting, and its value will settle as more samples arrive.
  • Change: the percentage change against the previous release.

Deploys can be created with the CLI, Node.js API, HTTP Site API or GraphQL API, or detected for you once a repository is connected with GitHub deployment tracking.

Filter to a single page#

To follow one page instead of the aggregate, choose it from the All pages selector at the top of the report. The chart and every panel then cover that page alone.

Change reporting timespan#

Choose a period from the control at the top right of the report. Each panel compares the previous period against the selected one, so read the percentage change alongside the value to spot trends worth acting on.