Working in projects has always been a team effort. Emerging trends, such as agile project management and team leadership, move towards more mandate to the actual team, rather than power to a single project manager. These trends make effective teamwork even more important. Another trend is working in distributed, or virtual, teams. Technology is a prerequisite for virtual teamwork and by using technology, saved event log data enable the possibility of analysing behaviors within teams. This thesis is an attempt to propose relevant project teamwork metrics that could be used to measure team effectiveness in digital team cooperation software such as project management systems or similar software needed especially for virtual project teams. The proposed metrics and threshold values are derived from previous research on Critical Success Factors (CSF) for project management and teamwork effectiveness. The areas of importance for teamwork metrics proposed in this thesis are Project team size, Communication, Location, Activities and Duration.

Much of earlier research on teamwork effectiveness was conducted using collocated teams. One such metric with high impact on effectiveness, is to have the correct project team size. For collocated teams, studies conclude the highest probability of reaching project maturity is in teams of five to nine members. In this thesis, a corre-lational study is conducted in an attempt to identify the best team size for virtual teams. In virtual teams, according to a study in 1996, the amount of communication is an important sign of team effectiveness. The average amount of communication was 3,7 times higher in highly productive teams.

In this study, using event log data from a project collaboration software called Projectplace SaaS, a "big-data-approach" analysis involving 5 313 virtual project teams is carried out. The analysis shows teams of three or four project team members having, on average, 60.4 percent more communication than teams of other sizes (ranging from one to twenty project team members). This indicate possibilities for higher effectiveness in team sizes of three and four team members in virtual teams.