The collaboration concept is a crucial element involved in the reliability of the collaborative system. Collaboration does not depend on collaboration itself; that is, a collaboration established at some point of the past influence’s collaboration calculation at present. The collaboration value depends on factors that are invariable over time, as well as it is time dependent. Then, the assessment of the collaboration value critically depends on time. In this paper, we discuss the effect of time on collaboration, which measures the variation over time in the reliability level of a collaborative system. We suggest a new model for temporal variation of collaboration value. The simulation shows that our model provides more flexibility in interpreting the decay of collaboration over time. We assume that the efficiency of our model is reposing on its ability to measure the temporal variation of the collaborative system reliability, which is lacking in existing models.