Does the Documentation of Design Pattern Instances Impact on Source Code Comprehension? Results from Two Controlled Experiments

We present the results of a controlled experiment and a differentiated replication that have been carried out to assess the effect of the documentation of design patterns on the comprehension of source code. The two experiments involved Master Students in Computer Science at the University of Basilicas a and at University of Salerno, respectively. The participants to the original experiment performed a comprehension task with and without graphically-documented design patterns. Textually documented design patterns were provided or not to the participants to perform a comprehension task within the replication. The data analysis revealed that participants employing graphically documented design patterns achieved significantly better performances than the participants provided with source code alone. Conversely, the effect of textually documented design patterns was not statistically significant. A further analysis revealed that the documentation type (textual and graphical) does not significantly affect the performance, when participants correctly recognize design pattern instances.