Customers who bought wine but not beer comprised 5.8% of the total number of customers, and those who bought beer but not wine constituted 6.6% of the total number; 1.2% of customers bought both wine and beer. In general, customers who bought both beer and wine bought more food items and spent more money than other customers (). A smaller proportion of beer buyers purchased fruit or vegetables, bread, poultry, milk, cereals, and sweets than other customers (). A higher proportion of wine buyers than beer buyers bought all the food items, except for soft drinks, which were bought by a higher proportion of the beer buyers, probably because people who bought beer also bought fewer items and spent less than wine buyers (). When we stratified the analyses according to the number of items bought and the total amount spent, the patterns were the same for all strata; therefore, the figures show the results of the merged strata.
shows the results of the correspondence analysis. Dimension 1 (vertical axis) explains 83% of the χ2 value and dimension 2 (horizontal axis) explains 17%. Dimension 1 is linked to wine, beer, chips, soft drinks, veal, oil, and olives at one end and milk, cereals, cold cuts, and low fat products at the other end. Dimension 2 is linked to soft drinks, beer, lamb, chips, butter, sausages and pork at one end and olives, oil, veal, wine, and beef at the other end. The correspondence plot shows that beer buyers are more likely to buy chips, soft drinks, and lamb and that wine buyers are more likely to buy oil, olives, veal, and beef. Milk, bread, pasta, and cold cuts, which we interpreted subjectively as everyday purchases, were found at the low negative end of dimension 1, whereas chips, alcohol, veal, spices, and beef, which we interpreted as weekend shopping, were at the high positive end. Similarly, we interpreted dimension 2 as a Mediterranean diet (oil, wine, veal, low fat meat, and low fat cheese) at the low negative end and a traditional diet (beer, butter, sausages, and pork) at the high positive end.
Food items bought by wine and beer buyers. Food items that are highly correlated and more likely to be bought together are closer to each other
shows the results of the logistic regression. Comparing wine and beer buyers, we found that beer buyers made fewer purchases of olives, fruit or vegetables, cooking oil, poultry, low fat milk, low fat cheese, and low fat meat than wine buyers and more purchases of soft drinks, lamb, sausages, butter or margarine, pork, chips, cold cuts, sugar, and ready cooked dishes.
Likelihood of beer and wine buyers buying items of food. Items with an odds ratio lower than 1 are bought more often by wine buyers and items with an odds ratio higher than 1 are bought more often by beer buyers