Sven Amann

Are Code Reviews Worth It? Insights from 16 Years of Review Data

Every hour spent on code review yields half a bug fix and one maintainability improvement. This talk presents the data to prove it.

Are Code Reviews Worth It? Insights from 16 Years of Review Data
#1about 2 minutes

Proving the value of code reviews with data

The talk aims to provide quantitative data from 16 years of development to convince management of the benefits of code reviews.

#2about 3 minutes

Context of the 16-year development data set

An overview of the Teamscale product, its 1.5 million line codebase, and the team's development velocity provides context for the data analysis.

#3about 3 minutes

The asynchronous code review workflow in practice

The team uses a feature branch workflow with asynchronous reviews in GitLab, where the reviewer has the final authority to merge.

#4about 2 minutes

Defining value vs cost for code review analysis

The analysis frames the "worth" of code reviews by comparing their value (code improvement, knowledge sharing) against their cost (developer time).

#5about 2 minutes

Analyzing the time cost of the review cycle

An analysis of time logged on tickets reveals the distribution of time spent in the "in review" and "in rework" phases.

#6about 6 minutes

Investigating outliers where review time is high

An example ticket shows how scope creep and implementing new requirements during the review cycle can significantly inflate review time data.

#7about 4 minutes

Quantifying the cost and value of code reviews

Data shows reviews add 33% to development time while providing an average of 1.6 bug fixes and 5 maintainability improvements per ticket.

#8about 1 minute

Conclusion: Weighing the costs against the benefits

Weighing the 33% additional time cost against the benefits of bug fixes, maintainability improvements, and knowledge sharing confirms their value.

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