In this blog, we have occasionally used networks to illustrate differences between countries in some socially determined characteristic. This is a form of exploratory data analysis. Today's example concerns which characteristics of the label are used when choosing a bottle of wine for purchase.
The data are for a 12-country survey co-ordinated by:
Steve Goodman (2009) An international comparison of retail consumer wine choice. International Journal of Wine Business Research 21: 41-49.The data were collected using different techniques in each country — some data were collected online, others as mall intercepts, in-store surveys or various combinations. However, in each case the people were asked to rank the following 13 characteristics in order of importance for choice "the last time you bought a bottle of wine in a shop to have for dinner with friends":
- Tasted the wine previously
- Someone recommended it
- I read about it
- Origin of the wine
- Grape variety
- Brand name
- Matching food
- Medal or award
- Information on back label
- An attractive front label
- Information on the shelf
- Promotional display in store
- Alcohol level below 13%
For the exploratory data analysis, I first used the manhattan distance to calculate the similarity of the different countries and label characteristics, based on their choice scores. This was followed by a neighbor-net analysis to display the between-country and the between-characteristic similarities as separate phylogenetic networks.
The network for the 12 countries is shown in the first graph. Countries that are closely connected in the network are similar to each other based on the choice of label characteristics, and those that are further apart are progressively more different from each other.
Clearly, there are no strong groupings of countries, indicating that the people all do things differently. Nevertheless, there are some patterns here.
Some of the country associations are to be expected, based on the similarities of their cultures, such as the grouping of Australia, New Zealand and the USA. However, it might be expected that the other English-speaking country, the UK, would be in the same group, rather than where it is, associated with the two Asian countries, China and Taiwan. Similarly, it might be expected that France would be associated with the other mainland European countries, Austria, Germany and Italy, but this association is only weak.
The source of these patterns becomes clear when we consider which wine-label characteristics were used to make the purchase choice. These are shown in the next network where, once again, characteristics that are closely connected in the network are similar to each other based on their ranking across countries, and those that are further apart are progressively more different from each other.
The characteristics that were consistently ranked highest are at the top-right of the network, progressing down to those ranked lowest, shown at the bottom of the network. Note that the label and its detailed contents are grouped at the bottom, along with shelf and promotional information. The rumor that a "nice label" is an important component of choice is not supported by these data. As the author notes: "it does appear that in-the-store / point-of-purchase / nice-labels information might in fact be too late to influence decisions" — people more often make their choice before they get to the store.
Instead, the contents of the bottle and its origin rank high, along with previous experience (awards and recommendations); but, not unexpectedly, nothing beats personal experience with the wine. One's own prior opinion is more important than anything else.
The somewhat unexpected location of France in the network arises because the French ranked "Matching food" as their top criterion, whereas most other people chose "Tasted the wine previously". However, for Italy it was a close-run thing between these two choices, making the Italians the closest to the French.
The unexpected location of the UK in the network arises because these three were the only countries where "Grape variety" was a long way down the choice list. This might be related to the fact that the British have long been wine consumers, back in the days when grape varieties were not prominently displayed on wine labels, unlike the situation for the "new world" wine consumers, where it is often the most prominent piece of information. However, traditional lack of interest in grape varieties would also apply to the other European countries.
Interestingly, China and Taiwan also put "Matching food" a long way down their lists, as did the New Zealanders, whereas Australia, the UK and the USA put "Matches food" near the middle of their lists. Thus, only half of the countries thought that this criterion, which is traditionally considered to be important, was of much interest. Anyone who has ever tried drinking a wine whose taste does not complement the accompanying food (as I sadly have) will thus think that half the world is crazy. Perhaps these people are not drinking their wine with a meal? Philistines!