Analysis of Sales Promotion Effects on Household Purchase Behavior

a positive correlation between the two purchase acceleration measures (timing and quantity)
means that households buy more but not sooner or buy sooner but not more <strong>of</strong> the product.
This positive relation is what we expect to find in general, because consumers cannot
purchase and consume infinite amounts <strong>of</strong> products. This relationship between interpurchase
timing and purchase quantity is also present when there are no promotions. Most households
do not have a fixed interpurchase time. Sometimes they shop once a week, but sometimes
more <strong>of</strong>ten or less <strong>of</strong>ten. When one buys more <strong>of</strong> a product, one will postpone the next
purchase. Snack categories might form exceptions, since buying extra volume during
promotional shopping trips could easily lead to category expansion. So we would expect more
consistency across reaction mechanisms for potato chips-candy bars than for pasta-c<strong>of</strong>fee.
In Table 8.6 only significant correlation coefficients between a subset <strong>of</strong> the reaction
mechanisms are included. These are: brand switching (BS), time acceleration (TA), net time
effect (TN), promotional quantity (QP), net quantity effect (QN), and category expansion
(CE). These are the direct and net effects <strong>of</strong> sales promotions.
Indeed, the results from table 8.6 show that a positive coherence is found between
the two net effect measures <strong>of</strong> purchase timing (TN) and purchase quantity (QN) for three
categories, candy-bars, s<strong>of</strong>t drinks, and fruit juice. No significant positive correlation
coefficients are found for purchase acceleration (TA) and purchased promotional quantity
(QP). Households do seem to use these two reaction mechanisms (purchase timing and
purchase quantity) for compensation purposes. Not during the promotional shopping trip
itself, but with the subsequent promotional shopping trip.
Based on the number <strong>of</strong> different pairs (15) that could have been found to be
significant for each specific product category, only a limited number <strong>of</strong> significantly
correlated pairs are found. But, we do believe that these significant findings represent actual
behavior and are not found by accident (especially not the coefficients found with the lowest
p-values).
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