Review Depth Metric

Definition

Review Depth measures the average number of review comments provided per merged Pull Request (PR).

It reflects the level of review activity associated with merged PRs during the selected time range.

Only merged PRs are included in this metric.  

How the Metric Is Calculated

Review Depth is calculated as: Total review comments on merged PRs ÷ Total merged PRs

The headline value is calculated using total comments and total merged PRs across the entire selected time range.

This is a weighted average and is not derived by averaging daily values.

What Is Counted

Included:

• Inline review comments
• General review comments
• Requests for changes
• Suggestions submitted during the review process

Not included:

• Approval events (unless accompanied by a comment)
• System-generated messages
• Automated workflow comments
• Comments added after the PR was merged

If a reviewer submits comments across multiple review cycles on the same PR, all comments are included in that PR’s total.

How the Metric Is Displayed in the Dashboard

The metric card displays two types of values:

1. Headline Value (e.g., 0.93 Comments per Review)

The large number at the top represents: Total review comments ÷ Total merged PRs across the selected time range

This is not a total comment count and not tied to a single day.

2. Time-Based Values in the Chart

The line chart shows Review Depth aggregated per time bucket (for example, daily).

Each point represents: Total review comments ÷ Total merged PRs within that specific time bucket

Clicking a point displays:

• The Review Depth value for that date
• The comments-per-review ratio for that period

Daily values are calculated independently for each bucket and do not average to produce the headline value.

Why This Metric Is Useful

Review Depth provides visibility into:

• The level of reviewer engagement
• The thoroughness of review cycles
• Patterns in review behavior over time

Higher values may indicate more detailed review activity.

Lower values may indicate minimal feedback or expedited approvals.

Interpretation requires context.

How to Interpret Review Depth

Review Depth should be evaluated alongside:

• PR Size
• Rework
• PRs Merged Without Review
• Time to Review

More comments do not automatically indicate higher-quality reviews. Context matters:

• Larger PRs typically generate more comments.
• Mature teams may require fewer comments.
• Extremely high comment counts may reflect unclear requirements or misalignment.

There is no universal benchmark. Sustained near-zero Review Depth may warrant investigation.

Data Sources

Derived from:

• Pull Request review events
• Review comments submitted before merge
• Merged PR records

Limitations

• Measures comment volume, not comment quality.
• Does not evaluate whether feedback was actionable.
• Small datasets may produce volatile averages.
• Changes in review workflow or automation may affect counts.

Review Depth should be interpreted as part of broader review health analysis.

Stakeholder Use Cases

Engineering Managers

• Monitor review engagement patterns.
• Detect superficial or overly intensive review behavior.
• Balance review depth with delivery speed.

Team Leads

• Identify inconsistencies in review participation.
• Coach teams on review standards.

Developers

• Improve submission quality to reduce unnecessary comment cycles.
• Understand review expectations.

Reviewers

• Maintain consistent review participation.
• Benchmark review engagement over time.