Forecasting sales

Sure this is possible, but as they say in the financial community, "past performance is not a guarantee for future returns." Having said that, it is necessary to find out what marketing and sales believes the growth or decline of any product will be. I think input here is important. A mature product may be declining in sales, however there may be a new and improved (TIDE) version to increase sales. I don't believe that you can straight line the trend. There are to many mitigating factors involved. However once you have agreed upon assumptions (ie. new products will grow at 30%, intermediate at 10% and mature will decline 7%), then you can apply formula to the trends.

So have you determined your assumptions for growth of your product lines? If you have and wish to share, then we can surely help you with your forecasting.

Alan