Second, even within the disciplinary limits, the econometric modeling literature contains gaps. Most of the studies look at price discounts rather than extra- product price promotions or other forms of sales pro- motion(seeTable1).Relatively little is understood about how sales promotions influence consumers’ choices about where to shop (the“store-switching” effect).There are very few studies from developing countries, even though this is where sales of packaged foods are growing faster than the relatively saturated markets of the devel- oped world,and where consumers are less familiar with many brands.Many of the available studies use rather old data from the 1970 sand 1980s,which was collected prior to the development of more recent sales promotional techniques and the rapid growth of large retailers who engage aggressively in promotional activities.