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How to Measure the Impact of AI Coding Tools on Your Team

How to tell whether AI coding tools are working: measure delivery, quality and developer experience against a baseline, and avoid activity metrics that mislead.

Bhavin Mistry October 11, 2026 10 min readLast reviewed

Topics:AI leadership and strategy

The dashboard shows engineers merged more code this month than last. Whether that is good news depends on what else moved: how often changes failed, how long review took, how many merges were reverted and how the engineers felt about the work. Measuring the impact of AI coding tools is mostly the discipline of not stopping at the first number that goes up.

TL;DR

Measure outcomes, not activity. Track delivery (how fast changes reach production and how often they fail), quality (rework, reverts, escaped defects), developer experience (a short, consistent survey) and cost per outcome. Record a baseline before the rollout, compare the same service against itself over time, and treat team-versus-team comparisons with caution. Report what changed, what did not, and what you cannot yet tell.

Why activity metrics mislead

Activity numbers are easy to collect, which is why they are everywhere: lines added, suggestions accepted, pull requests opened. They tell you the tool is being used. They do not tell you whether the team delivers better software.

Activity metrics

  • Lines of code, suggestions accepted, pull requests opened
  • Easy to collect, and tend to rise whenever a tool makes producing code easier
  • Cannot distinguish useful code from code that gets reverted
  • Invite gaming once people know they are watched

Outcome metrics

  • Time to deliver a change, how often changes fail, time to recover
  • Rework, reverts and defects that reached users
  • How developers say the work feels, asked the same way each time
  • Harder to collect, but they answer the actual question
Activity metrics versus outcome metrics

An illustrative example of the trap: a team adopts a coding assistant and pull requests per week climb. If review time also climbs and more merges are later reverted, the team has moved effort from writing code to reviewing and repairing it. The activity number looked like a win; the outcome numbers say otherwise. You only find out if you measure the outcomes.

Start with delivery: the DORA measures

The DevOps Research and Assessment (DORA) programme defines software delivery measures you can use for this. According to DORA's own metrics guide (read on 11 October 2026), the current set has five measures, in two groups.

Throughput

  • Change lead time: how long a change takes to go from committed to running in production
  • Deployment frequency: how often you deploy
  • Failed deployment recovery time: how long it takes to recover from a deployment that needs immediate intervention

Instability

  • Change fail rate: the share of deployments that need immediate intervention
  • Deployment rework rate: the share of deployments that are unplanned and caused by a production incident
DORA's delivery measures, in short

Check the guide for the exact current definitions before you wire them into a dashboard, because the set has changed over time. Two points from the same page matter for how you use them. They are best suited to measuring one application or service at a time, and the guide cautions against making disparate comparisons, against blending metrics across very different teams or organisations, and against competing with others, noting that isolating teams with specific metrics can lead to friction and finger-pointing. That fits the advice below: compare a service with itself.

Add a quality and rework view

Delivery speed means little if quality drops. Pick a small set you can already measure and keep the definitions fixed:

  • Reverts and hotfixes per period, for the same service.
  • Defects found after release, and where they were found.
  • Review effort: how long changes wait for review and how many rounds they take. AI-assisted changes can shift work onto reviewers.
  • Security and static analysis findings on changes, trended over time.
  • Definitions are fixed

    Good: Each metric is defined once, written down and unchanged during the study

    Red flag: The definition drifts, so before and after cannot be compared

  • A baseline exists

    Good: Several weeks of data from before the rollout

    Red flag: You started measuring after the tool arrived

  • Outcomes, not just activity

    Good: Delivery, quality and experience are all reported

    Red flag: Only counts of code or suggestions are shown

  • Context is recorded

    Good: Team changes, releases and incidents are noted alongside the data

    Red flag: A dip or spike is explained by guesswork

  • Limits are stated

    Good: The report says what the data cannot show

    Red flag: Correlation is presented as proof the tool caused the change

Is your measurement trustworthy?

Add developer experience, asked consistently

Numbers from systems miss how the work feels: whether engineers trust the suggestions, where time is lost fixing generated code, and whether the tool helps with the tedious or the hard parts. A short survey, asked the same way every quarter, fills that gap. Keep it to a few specific questions about concrete situations, such as how often generated code needed significant rework, and how confident people feel reviewing it.

Treat survey answers as perception, not measurement. Developers can feel faster while delivery measures stay flat, or the reverse, and both facts are worth knowing. The site's Developer Experience tool offers an eight-question pulse survey for AI coding tools to start from.

Take a baseline, then run a simple plan

  1. Weeks 1 to 4

    Baseline: collect delivery, quality and survey data before any rollout, and fix the definitions

  2. Week 5

    Roll out to a defined group, and record the tools, settings and any training given

  3. Weeks 6 to 12

    Collect the same measures and note releases, staffing changes and incidents as they happen

  4. Week 13

    Compare each service with its own baseline, read the survey changes, and write down what you cannot tell

A measurement plan (illustrative; adjust the lengths to your release rhythm)

If you can, roll out in stages so some services adopt later and act as a comparison. Be honest about the limits: teams that adopt early are often different from teams that adopt late, so a comparison group is a clue, not proof.

Pick the measure for the question

  • If

    Are changes reaching production faster?

    Choose

    Change lead time and deployment frequency, per service

    Because

    They measure delivery throughput directly

  • If

    Is quality suffering?

    Choose

    Change fail rate, reverts and defects after release

    Because

    Speed gains that cost stability are not gains

  • If

    Is review becoming the bottleneck?

    Choose

    Time and rounds in review

    Because

    Generated code can move effort to reviewers

  • If

    Do engineers find the tool useful?

    Choose

    A consistent developer experience survey

    Because

    System data cannot show how the work feels

  • If

    Is it worth the money?

    Choose

    Cost per outcome, from the full cost picture below

    Because

    Licence price alone says nothing about value

Which measure answers which question

Count the whole cost

Licence fees are the visible part. Include the time spent learning the tools, extra review effort, time fixing or reverting generated changes, any incident time linked to them, and the admin and security work to roll them out safely. Compare the total with the measured change in outcomes. The Engineering Productivity tool compares GitHub delivery and quality metrics before and after an AI coding tool rollout, week by week, with bots excluded and an optional control repository, which fits the baseline approach above. The AI ROI Calculator helps you set out cost and value assumptions explicitly, and every number you enter is yours to justify.

Do not present a percentage improvement you did not measure, and do not borrow one from a vendor's marketing. If a claim about productivity comes from outside your own data, cite the source and say how it was measured.

What not to do

  • Do not rank individual engineers by tool usage or output. It invites gaming and misreads context.
  • Do not compare teams with different work, services or release cadences as if they were equal.
  • Do not change a metric's definition mid-study.
  • Do not report a single average without the spread and the context.
  • Do not claim the tool caused a change you only observed alongside it.

Reporting back

A useful one-page report has five parts: what was measured and how, the baseline, what changed on each measure, what did not change or got worse, and what you cannot yet conclude with the next step to find out. Leaders can act on a report that admits its limits far better than on a bold number that collapses under questions. For the wider picture of how AI changes each stage of delivery, see the AI-native SDLC and the 90-day adoption playbook.

Frequently asked questions

How do you measure the impact of AI coding tools? Measure outcomes against a baseline: delivery measures such as lead time and change fail rate, quality and rework measures such as reverts and defects after release, and a consistent developer experience survey. Then compare each service with its own past, and state what the data cannot show.

Why are pull requests or lines of code a poor measure? They measure activity, which tends to rise with any new tool. They cannot tell useful code from code that is later reverted, and they can move effort from writing to reviewing. Outcome measures answer whether the team delivers better.

What are the DORA metrics? They are software delivery measures defined by the DevOps Research and Assessment programme. Its current guide lists five: change lead time, deployment frequency, failed deployment recovery time, change fail rate and deployment rework rate. Check the guide for the exact current definitions.

Can I compare teams using these measures? Be careful. DORA's guide says the measures suit one application or service at a time and warns that comparing or blending numbers across different contexts is misleading. Compare a service with its own baseline instead.

Do I need a baseline before rolling out AI coding tools? Yes. Without data from before the rollout, any change you see has no reference point. Collect several weeks of the same measures first and fix their definitions.

How do I include developer experience? Run a short survey with the same specific questions each quarter, covering how often generated code needs rework and how confident people feel reviewing it. Treat the answers as perception, and read them alongside the system measures.

What does it really cost to adopt AI coding tools? Beyond licences, count learning time, extra review effort, time fixing or reverting generated changes, related incident time, and rollout and security work. Compare the total with the measured change in outcomes.

Sources

  • DORA metrics guide (DORA), read on 11 October 2026: the five delivery measures and the guidance on one service at a time and on comparisons

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