In Graph 1 in the main article, the pattern shows changes in the sign of a trend-line slope, from positive to negative and vice versa. This kind of slope change occurs when the trend goes from up to down and from down to up. These patterns are important to look for in your data. You might want the ability to isolate items that have one or more slope changes. For example, you might need to find customers whose sales have changed from positive growth to negative growth (i.e., customers whose purchases have decreased).

This MDX puzzle uses the FoodMart Sales cube. Write an MDX formula that counts the slope sign changes in a trend line across a series of months. Just for fun, find all the product brand names that have six slope sign changes during the months of 1997.