Modeling the impact of a learning phase on the business value of a pair programming project

Pair programmers need a "warmup phase" before the pair can work at full speed. The length of the learning interval varies, depending on how experienced the developers are with pair programming and how familiar they are with each other. We study how large the impact of the lower pair productivity during warmup is on the business value of the pair programming project. To this end, we extend our net present value model for pair programming to explicitly include a learning interval for pairs. We then carry out a simulation study where we vary the shape of the learning curve, the length of the learning interval, the final productivity level of the pairs, the market pressure, and the size of the workforce. Our simulations show that the cost of the warmup phase is reasonably small compared to the project value, but nonetheless must be taken into account when estimating the project. Our results also suggest that the learning overhead is not an obstacle to introducing and using pair programming in a real environment.