Forecasting is a fun challenge. Its filled with assumptions, guesses, and statistics (lies?). But no one can deny the importance of forecasting in new product investment and sales planning. As a product manager, its one of the fundamental activities that needs to be owned by you. So how do you figure how much you can sell next year for you product offerings? You could make guesses at salesperson efficiency, or figure out how many people you can reach online for direct sales channels and guess at a 1% conversion rate.
A method I really like is working backwards from how much your competitors are spending in marketing and sales relative to their total revenue from products. For instance, let’s say your competitors spend 40% of their revenues on marketing/sales. Assume that is your new customer acquisition cost for your product. Now, assuming you’ve figured out how many of your product units you need to sell to match your company’s expected ROI, you’ve got the basis for how much you need to spend in marketing to get there, or how hard your marketing dollars could reasonably be expected to work after good tactical decisions are made.
i.e. 50 target units for 30% ROI is the target, $400 customer acquisition costs leads to $20K needed for marketing to hit the units target
Now work that backwards to figure out what your achievable market share is for the next year (assuming you have some idea what the demand looks like for the next year)…and extrapolate for growth to move towards a more realistic total product lifetime market share target.