The initial 15% increase in code development expense is recovered in the reduction in defects.
In the quantitative study at the University of Utah, the pairs not only completed their programs with superior quality, but they consistently implemented the same functionality as the individuals in fewer lines of code. Pairs consistently report that they solve problems faster...
Given that a short time to market is decisive for the success of a project, adding developers to form programmer pairs can speed up the project and increase its business value despite the increased personnel cost. This is due to the fact that programmer pairs can be expected to have a higher productivity and code quality as compared to single programmers.
General agreement that pair programming leads to increased quality, and the code produced by the paired teams was easier to read and to understand, facilitating maintenance.
The case study showed that programmer pairs spent much shorter period of time in completing the task than individuals. Programmer pairs completed the tasks with higher quality than individuals since their programs passed more test cases than those by individuals. The modules in the programs written by pairs have higher cohesion and more meaningful variable names. Paired programmers also wrote many more lines of code per hour than individuals.
To the surprise of the managers and participants, all the teams (pairs) outperformed the individual programmers, enjoyed the problem-solving process more, and had greater confidence in their solutions. The groups completed the task 40% more quickly and effectively by producing better algorithms and code in less time.
In their XP experience, the majority of the defects they found could be traced back to a time when a programmer worked independently. In fact, in their Chrysler Comprehensive Compensation project during the last five months before first production, the only defects that made it through unit and functional testing were written by someone programming alone.
Results indicated the pre-release defect density of the four products decreased between 40% and 90% relative to similar projects that did not use the TDD practice. The teams experienced a 15-35% increase in initial development time after adopting TDD. The assessment as to whether the reduction in pre-release defect density is worth the increase in initial development time is somewhat subjective.
"Software is eating the world" - becoming the differentiator for industries that were previously thought to be more manual. In software organizations across all industries, 80% practice agile development, 85% use a DVCS such as Git, and 65% practice Continuous Delivery (CD). 80% of respondents said the average development team in their company has 10 or fewer members. 56% reported using containers to spin up test, staging, or production environments.
High-performing organizations deploy 30x more frequently with 200x shorter lead times; they have 60x fewer failures and recover 168x faster. Lean management and continuous delivery practices create the conditions for delivering value faster, sustainably. IT managers play a critical role in any DevOps transformation.