Review of Science Daily: Reusable Shopping Bags Encourage Shoppers to Buy Produce—and Junk Food?
Science Daily asserts that “bringing reusable bags” to shop at grocery stores supposedly “influences the things you buy.” But the influence on purchases most likely stems from multiple factors beyond simply just “bringing re-usable bags.”
Causation assumes the elimination of all other possible variables contributing to an outcome. When more than one possibility exists for an outcome, correlations apply. Here, the writer verbatim concludes, “the first to demonstrate that bringing one’s own grocery bags causes significant changes in food purchasing behavior,” merely citing, “card-holder data generated from a single location,” as evidentiary support.
First, Science Daily lacks definitive proof that reusing shopping bags causes any let alone “significant changes” in buying behavior, and to infer as such wrongly assumes no other possible reasons for the change in consumer purchasing patterns. Secondly, the mere unrepresentative data alone fails to establish a sufficient link necessarily between reusing shopping bags and changes in buying behavior.
For example, the sample examined only one grocery store location for a limited duration of approximately two years. Such a sample assumes everyone in the population exudes identical purchasing patterns for grocery shopping. Buying behavior may change for a whole concomitant assortment of imponderable reasons unrelated to the bags.
Additionally, the limited time duration neglects macro-economic influences on buyer spending, an assumption that people may behavior differently during more sluggish economic cycles. These variables reasonably support the probative inference of an insufficient causal link between reusing shopping bags and buying behavior because the studies neglect other possibilities.
Therefore, the article mistakes causation for correlation because buying behavior may stem from multiple factors unrelated to subsequent purchases.
Furthermore, the article offers no support for its conclusion that allegedly, “virtuous feelings” about “environmental responsibility,” necessarily precipitates a desire “to treat oneself with junk food.” Even if customers exhibit such sentiments, assuming can even accurately assess “virtuous feelings of environmental responsibility,” such a conclusion lends no support for buying behavior.
Ultimately, Science Daily remains most susceptible to the criticism of mistaking a sufficient and necessary condition. This article assumes the validity of studies which mistake correlation for causation, namely, overlooking other possible influences beyond reusable bags for junk food purchases.
Science Daily: Reusable shopping bags encourage shoppers to buy produce—and junk food?
American Marketing Association, July 7, 2015, p. 1-2.