There are a number of excellent resources available to help with the practices and methods of forecasting, including many books and software packages, both small and large. Since this site is aimed at business leaders, however, the primary recommendations are in a different direction.

As you look over the Laws of Forecasting, you'll notice that many of these issues have to do with errors in various assumptions (trends ending, methodologies, forecast validity, data validity, etc.). Traditional forecasting resources generally mention these topics, and one such book is Business Forecasting with Student CD. However, there don't seem to be any good forecasting books that really explore these topics as deeply as they should for the users of those forecasts. A solidly built forecast using the latest analytical tools just looks so right, especially to those of us with an analytical bias. The issues around the assumptions deserve very careful thought.

Assumptions can be very difficult to uncover, and once identified, they can be difficult to evaluate. Three books come to mind as good places to start in thinking about this at a higher level. By knowing the right questions to ask -- of yourself and others -- any forecast can be improved. Or if nothing else, it can be possible to use it more appropriately.

As a great place to start with this process, consider The Fifth Discipline: The Art & Practice of The Learning Organization, by Peter Senge. This book was first written in 1990, and was updated in 2006. It is not a forecasting book, but it can be very useful as a way to think about assumptions ("mental models"), and system dynamics ("systems thinking"). If you've read it before, it could be a good thing to review.

As an expansion of Peter Senge's ideas on systems thinking, Business Dynamics: Systems Thinking and Modeling for a Complex World provides a very solid description of system dynamics in businesses. The field of System Dynamics, which happens to be the specialty of our consulting practice, helps to explain the important side-effects, delayed effects, interactions, and feedback loops that occur within businesses (and within systems of all types). The Laws of Forecasting state that "all trends end". System Dynamics help to explain how and why they might end, and what that change might look like. A trend could end in a collapse (such as Easter Island), a flattening (such as a saturated market), or an oscillation (such as many maturing businesses experience). Knowing that they will end is important. Knowing the how, why, and when is much more important, and system dynamics can help provide some answers. Contact us for more information here, or to discuss a possible project.

A final recommendation to challenge some assumptions is The Black Swan: The Impact of the Highly Improbable. This one might not seem to be as relevant as the other resources, and once again, is not a forecasting book. But it might give you some good ideas. Finally, please contact us if you have more specific questions, comments, or ideas for resources to recommend here.