Additive models for dependent cell populations.

We propose an additive model for cell population growth which allows for positive correlation between sister cell lifetimes but arbitrary correlations between mother and daughter cell lifetimes. In the model each cell lifetime is the sum of two independent components, one of which is shared with its sister cell and which is also a function of the components of the lifetime of their mother. Assuming that the components follow a gamma distribution, the model is fitted to cell lifetime data of EMT6 cells obtained by the method of time-lapse cinematography.