1% low-fat milk has perks!: An evaluation of a social marketing intervention.

This study evaluated the effect of a 12-week social marketing intervention conducted in 2012 promoting 1% milk use relying on paid advertising. Weekly milk sales data by type of milk (whole, 2%, 1%, and nonfat milk) were collected from 80 supermarkets in the Oklahoma City media market, the intervention market, and 66 supermarkets in the Tulsa media market (TMM), the comparison market. The effect was measured with a paired t-test. A mixed segmented regression model, controlling for the contextual difference between supermarkets and data correlation, identified trends before, during, and after the intervention. Results show the monthly market share of 1% milk sales changed from 10.0% to 11.5%, a 15% increase. Evaluating the volume sold, the monthly mean number of gallons of 1% milk sold increased from 890.5 gal (SD = 769.8) per supermarket from before the intervention to 1070.7 gal (SD = 922.5) following the intervention (t(79) = 9.4, p = 0.000). Moreover, average weekly sales of 1% milk were stable prior to the intervention (b = - 0.2 gal/week, 95% CI [- 0.6 gal/week, 0.3 gal/week]). During each additional week of the intervention, 1% milk sales increased by an average of 4.1 gal in all supermarkets (95% CI [3.5 gal/week, 4.6 gal/week]). Three months later, albeit attenuated, a significant increase in 1% milk sales remained. In the comparison market, no change in the market share of 1% milk occurred. Paid advertising, using the principles of social marketing, can be effective in changing an entrenched and habitual nutrition habit.