Reading historical wellbeing from books

Should you aim to increase the GDP of a country, or should you invest in increasing life expectancy?

One way to estimate which would make people happier is to look at the historical wellbeing of the population, and old books may provide the key.

A novel approach for creating a wellbeing indicator to help economists and policymakers was just published in Nature Human Behaviour by an international team of researchers.

“We took several databases of digitised text going back over the last 200 years, and these represent something like 6 to 7 percent of all published books over this time period. And that's magical in a way because it taps into the zeitgeist of people's changing attitudes and beliefs about things,” says lead author Thomas Hills from the University of Warwick.

Using these digitised books, the researchers computed a national annual National Valence Index (NVI) by counting the frequency of positive and negative words in each of the books that were published in a certain year and a certain country. Plotting this annual NVI we get a historical chart that seems to track the subjective wellbeing of the population.

How accurate is it? A basic validation can come from just looking at these charts, where we can observe a decrease in life satisfaction during the war periods, such as World War I and World War II, or the Civil War in the US. This suggests that the mood of the books during those periods was more somber, potentially fitting in with the general mood of the population as well.

The researchers also validated the NVI statistically, using the available data from the Eurobarometer survey, a regular public opinion survey run in Europe that asks a sample of the population how satisfied they are with the life they lead.

The Eurobarometer survey has first been run in 1973, and before that there is little data on wellbeing, a gap that this study aims to fill in.

By comparing the NVI and Eurobarometer survey measures for the overlapping period for the three European countries that they analysed, the UK, Germany and Italy, the authors find that they are highly correlated, and so the NVI seems like a good indicator for past wellbeing.

As to whether you should increase GDP or life expectancy, this study suggest the latter: increasing the average life expectancy by a year is equivalent to as much as 4.3% annual growth in GDP per capita.

“We’re getting to the point where we can look back in time and we can see the consequences of different decisions that we've made,” says Thomas, “and hopefully that gives us a handle on the kinds of decisions we can make now to improve our well being in the future.”

The need to consider the wellbeing of the population is becoming more and more important in policy work, and being able to look back at historical values, even if estimates, can be a very useful tool in designing better policies.