Forecasting techniques (using the term forecasting in its broadest sense) can be divided into two categories: Qualitative and Quantitative.
Qualitative Techniques
While these techniques are based on good theory and can yield valuable information for marketing decisions, they are not intended directly to support inventory decisions.
Rather, they are intended to support product development and promotion strategies.
Data gathered by these methods should be considered in some aggregate inventory or capacity planning decisions, but should not be the sole data source for such decisions.