Decisions in the supermarket: the impact of offers on the shopping basket


Whether we are the people who prepare a painstaking shopping list, or those who improvise while walking the corridors, when we enter a supermarket we believe ourselves absolute owners of our choices. However, these spaces are not only home to food and household items, but also host carefully designed sales strategies that influence our behaviour.

In current times, where inflation is tightening and prices are skyrocketing, our eyes are drawn to the eye-catching posters of outstanding offers.  We have modified consumer habits in an effort to control expenses, and promotions have taken on a significant role almost inadvertently. But, what is their real impact in what we end up bringing home?

Wafa Mehaba, PhD student and expert in analysing the effects of promotions on household spending in CREDA, helps us understand the power these strategies have on our buying behaviour. To do this, it uses data from the consumer panel, where the different purchases made by a representative sample of the population of Catalonia are presented.



Except for the festivities, where cars are filled with delicacies and luxuries and emotions drive our elections, promotions, a cultural phenomenon in some countries such as the United States, used to have little importance in the Spanish market.

However, the increase in the cost of food has transformed the way we buy. As a result, previously scarce offers have become ubiquitous, used by establishments to attract and retain customers. The higher and better discounts, the more people are attracted to the promise of savings. Do they keep that promise? Not really.

Buying on promotions doesn’t mean you spend less money. You spend more! It’s a deception to believe you’re saving”, Mehaba explains. “This happens because when we perceive a price drop in a product, we tend to buy larger quantities, or we opt for more expensive products with the part we save from promotions”, she adds. And this is not the only pernicious effect of these practices, since the dynamics created by this type of campaign go beyond increasing the consumption of discounted products.



There are basic products that, up or down prices, will remain in our basket”, the PhD student tells us. That is, we will not buy more potatoes if they are cheaper, but we will not do so if they go up in price. It is not the same with foods that we consider of greater value, “promotions have a strong impact on the purchases of fish, prepared dishes, fruits and juices, sweets and desserts, as well as alcoholic beverages”, says Mehaba.

As a chain reaction, these changes can have unexpected consequences. To begin with, adjustments are given in consumption, “when promoting a specific type of food, people spend more in that category, but less in others”, says the expert. “This means that you don’t buy more, but you distribute the budget between different food categories differently. A small but significant budget allocation”.

For example, when vegetables and fruits are on offer, there is a small decrease in the consumption of sugar, confectionery and prepared desserts. However, by reducing the prices of the latter, the decrease in the consumption of vegetables is much greater. That is, promotions in one type of food affect the consumption of another, in addition, the magnitude of the impact is much greater in one sense than in the other and, in this case, promotes less healthy choices.

With these results, Mehaba aspires to see research like the one he is doing at CREDA influence legislative changes: “for example, regulate more promotions of products classified as less healthy rather than just increase their price, because even when they go up, people keep buying”.

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