Analysis of Sales Promotion Effects on Household Purchase Behavior

studies. <strong>Promotion</strong>s do not lead primarily to a reallocation <strong>of</strong> current expenditures by
households across items within a category.
But, the decomposition dealt with thus far assumes that consumers first decide when
to buy and then what and how much. The focal point was whether a promotion resulted in a
change in interpurchase time or not. Is it realistic to assume that consumers first decide when
to buy when performing across product category research? A consumer does not visit a store
for each product category separately. Normally, purchases are made within more than one
product category during one and the same shopping trip. When a consumer is shopping, he or
she may run into a promotion for a product category from which he or she did not intend to
buy, where the promotion is for a non-favorite brand. This can result in accelerated nonfavorite
brand purchases. Are these accelerated purchases mainly due to a change in purchase
timing or due to a brand switch? Van Heerde et al. (2001) assigned these accelerated
purchases to a change in purchase timing, as the increase in own-brand sales cannot be
assigned to current cross-brand effects. But, isn’t more logical to assign these increased unit
sales to brand switching instead <strong>of</strong> a change in purchase timing? When assigning the entire
effect to brand switching, an upper limit is obtained for the brand switch effect, whereas the
assignment procedure followed before provides a lower limit for the brand switch effect. The
effect <strong>of</strong> combined responses <strong>of</strong> changes in purchase timing and brand choice is assigned to
brand switching instead <strong>of</strong> purchase timing, as depicted in Figure 8.3. The focal point in this
approach is whether current promotional unit sales come from regular consumers (consumers
that also buy the brand when it is not on promotion) or from non-regular consumers
(consumers who switched to the promoted brand). A manufacturer is not so much interested in
drawing purchases from other shopping trips. A manufacturer is interested in the ability <strong>of</strong>
sales promotions to draw consumers from competitive brands.
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