A preliminary study on the impact of a pair design phase on pair programming and solo programming

The drawback of pair programming is the nearly doubled personnel cost. The extra cost of pair programming originates from the strict rule of extreme programming where every line of code should be developed by a pair of developers. Is this rule not a waste of resources? Is it not possible to gain a large portion of the benefits of pair programming by only a small fraction of the meeting time of a pair programming session? We conducted a study to answer this question. We split the pair programming process into a pair design and a pair implementation session and started to analyze the impact of the pair design session on pair implementation and solo implementation. Our data shows that after pair design took place the solo implementation phase is 21 percent cheaper than the pair implementation phase.