Case studies are used for monitoring projects, activities or assignments. Data are collected for a specific purpose throughout the study and based on the data collection, a statistical analysis can be carried out. The case study is normally aimed at tracking a specific attribute or establishing relationships between different attributes. The level of control is lower in a case study than in an experiment. The case study is an observational method while the experiment is a controlled method […]. The case study may be aimed at building a model to predict the number of faults in testing. Multivariate statistical analysis is often applied in this type of studies. The analysis methods include linear regression and principal component analysis […].

Wohlin, C., Runeson, P., Höst, M., Ohlsson, M., Regnell, B., & Wesslén, A. (2000). Introduction to Experimentation in Software Engineering. [-]