I am trying to model future sales data for products which have very low sales volume. I am a programmer with a smattering in statistics, so I apologise in advance if this qustion is naive!
My question is what distribution is most suitable for my sales profile and is it possible to verify the distribution. The exact framing of the problem is that we might have a product that has say 6 units of inventory and we may sell 8 units a year with a "standard deviation" of 5 units (i.e. the sales are lumpy so we calculate a standard deviation, but its not really a normal distribution)...we want to say with a certain probability how many days inventory we have left. For high volume products we can assume the normal distribution and its pretty easy to back out the days inventory left. However for low volume products we can't assume normal distribution (as obviously it is bounded by the fact that we can't have less than 0 sales). I have looked at Poisson, but I am not sure if that is the most suitable.
Could someone point me to some resources that would help me identify the right model/technique to use?