Despite the success of plastic bag charges in the UK, there are still around a billion single-use plastic bags bought each year in England alone (DEFRA, 2018), and politicians are currently debating whether to double the 5 pence charge to 10 pence (Rawlinson, 2018). Previous research has identified motivations for bringing personal bags to the supermarket (Jakovcevic et al., 2014; Poortinga et al., 2016) but little is known about whom is continuing to regularly purchase plastic bags after the levy. In this study, we harness the power of big data to investigate who the regular plastic bag buyers are that future campaigns ought to target.
We utilise a dataset of 12,968 questionnaire responses measuring demographics and individual differences matched to respondents' loyalty card transaction data from a UK health and beauty retailer. We used the transaction data to identify regular single-use plastic bag buyers and non-bag buyers in the real world. We optimised different prediction models and evaluated them using out-of-sample testing. A logistic regression model performed the best, predicting regular bag buyers with 76% accuracy.
Figure 1. A graph to show the number of sales of single use plastic bags per 1000 items purchased in England each week by the survey sample (N = 12,968). Week 44 is the week of Halloween, week 48 the week black Friday occurred, and week 52 is the week of Christmas.
Figure 2. A map of the UK showing the mean number of bags sold by the retailer per 1000 items bought in that region. The bag sales were calculated using the full survey sample of 12,968 people.
The results showed that England had significantly less bag sales than Wales, Northern Ireland, and Scotland per 1000 items in the 9 months after the English levy. Across the UK, more bags per 1000 items were bought during the Christmas festive period. Shopping frequency, amount spent, age (negatively), frugality (negatively), income, impulsivity, a present time focus, and Openness significantly predicted regular bag buying. Notably, climate change concerns did not. In summary, this research has identified a young, high-income demographic of regular bag buyers to target. The additional insights that this sub-population are impulsive and unconcerned with climate change also helps to inform the content type and communication style for future plastic bag reduction campaigns.
Table 1. Logistic regression results.
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