New approach to study food purchases shows behaviours are surprisingly stable

In the LoCard study, conducted by Tampere University and the University of Helsinki, researchers analysed the grocery purchases of nearly 30,000 people from September 2016 to December 2018.

The research identified nine distinct food purchase behaviours, which could be grouped into three main categories: health-oriented, discretionary-oriented, and baby-oriented.

The study shows that food purchase behaviours in Finland are relatively stable. The short-term likelihood of transitioning from one purchase behaviour to another was fairly low (<5%), with the exception of the baby-oriented purchase behaviour. As young children grew older, households tended to transition from the baby formula and food purchasing behaviour to other purchase behaviours, most commonly to the discretionary-oriented behaviours, like ‘convenience’ or ‘sugar-sweetened beverages and snacks’.

The study analysed the food purchases of nearly 30,000 participants holding an S Group loyalty card. The participants consented to the use of their food purchasing data and completed a background survey for demographic characteristics (e.g. age and gender).

Health, discretionary and baby orientations 

The researchers identified four health-oriented purchase behaviours: balanced, home cook, flexitarian, and planetary. Although these purchase behaviours were distinct, they all reflected a generally healthy diet and followed national nutrition recommendations in effect at the time of the study for vegetables, fruits and berries, and red meat. 

The study also identified four discretionary-oriented purchase behaviours, which included 1) traditional, 2) convenience, 3) sugar-sweetened beverages and snacks 4) beer, sweets and treats. In these purchase behaviours, the share of vegetables, fruits and berries was relatively low, even though the purchases in the first two groups were diverse in other ways. 

In addition, the study identified a baby-oriented purchase behaviour that included the purchase of baby formula and foods. In addition to infant formula and baby foods, the purchases in this group varied and included a wide range of products.

New approach identifies changes in purchase behaviour

The study demonstrated that Hidden Markov Models are highly suitable for analysing large-scale, longitudinal food purchase datasets. Using a Hidden Markov Model, the researchers found, for example, that the probability of transitioning from one purchase behaviour to another similar type (e.g. flexatarian to planetary) was substantially higher than the probability of transitioning between different behaviours, such as a discretionary-oriented behaviour to a health-oriented one.

“Purchase habits do not usually change overnight since change tends to happen in small steps,” says Postdoctoral Researcher Anna Ruokolahti.

Purchases reflect age, gender and family situation

Food purchase behaviours varied considerably across population groups. Women, older adults, and childless households were more likely than others to exhibit health-oriented purchase behaviours.

Age, in particular, was strongly associated with food purchase behaviours. Among older participants, balanced and home cook purchase behaviours were more common, whereas young adults were more likely than others to exhibit more plant-based food purchase behaviours (i.e., flexitarian and planetary).

The stability of purchase behaviours was especially pronounced among participants over the age of 60, and even when changes occurred overall, they were generally gradual. Those with a health-oriented purchase behaviour usually transitioned to another health-oriented purchase behaviour, while those with discretionary-oriented purchase behaviours typically transitioned to another purchase behaviour within the discretionary-oriented group.

Young adults and families with children shifted their purchase behaviour more frequently than other groups, suggesting that their purchasing habits may be more flexible.

“This seems to indicate that young adults and families with children are more open to behaviour changes and may therefore be more receptive to adopting new, healthier dietary habits. Changes may also be related to life-course transitions, such as changes in family structures or routines,” Ruokolahti says.

The study was funded by the Research Council of Finland and the EU Horizon FoodDataQuest programme.

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