# Time series data distribution forecast?

While having chronically data of population growth (registered users of a site), I want to compute a function that approximates future growth, based on past data. Also, what we ll be the distribution of that function? What is the distribution of interarrivals between consecutive registrations.

You should check out the forecast package in R, specifically the ets() and auto.arima() functions. Both of these will fit a model to your historic data, and allow you to forecast into the future with confidence intervals. Note IrishStat's cautions about using a holdout sample to verify your forecasts as well as the particulars of ARMAX modeling (which auto.arima() can handle).