Final answer:
A combination of quantitative and qualitative forecasting is used when both numerical data trends and the underlying reasons for those trends need to be understood, which is common in business, sociology, and geography.
Step-by-step explanation:
One would utilize a combination of both quantitative and qualitative forecasting when there is a need to understand both the numerical trends and the underlying reasons or motivations behind those trends. This is often important in fields such as business, sociology, and geography. Quantitative forecasting, which might include statistical analysis of numerical data like a projection of a 5% annual growth rate, is helpful for identifying patterns and making predictions based on measurable data. Conversely, qualitative forecasting delves into the 'why' and 'how' behind the data through methods like in-depth interviews and content analysis, providing context that quantitative data alone cannot convey. For example, in business, quantitative data can show us how many units of a product were sold, while qualitative data can give insights into consumer satisfaction and the reasons behind purchasing decisions. In social sciences, while quantitative data might reveal demographic patterns, qualitative data uncovers the complex human behaviors driving those patterns. Similarly, geographers might use quantitative data to identify geographic trends but need qualitative information to understand the specific local factors influencing those trends.