Do they mean us?
David Cameron told the CBI yesterday that the government would pursue, in his words, "a relentless focus on growth".
The institute is part of a global movement arguing that, in trying to nail what we mean by social progress, for too long we have had "a relentless focus on growth" rather than trying to measure a nation's well-being.
Robert Kennedy said in 1968 that "Gross National Product...measures everything except that which makes life worthwhile", and when I interviewed David Cameron in 2006 he told me that government "should be thinking not just what is good for putting money in people's pockets but what is good for putting joy in people's hearts".
Writing in the Wall Street Journal to launch Legatum's index, the former Business Secretary Lord Mandelson says something very similar:
"To use economic measurements alone to gauge the success of a nation would be equivalent to assessing the entire condition of a man simply by looking at his bank balance. True enough we may discover whether the man is rich or poor but we learn nothing about his character, his enjoyment of life, the state of his health, the quality of his education or his attitude toward the people around him."
On the day that many eyes will be looking at the GDP figures, this Prosperity Index tries to widen the focus and ask how countries around the world, including Britain, measure up based on hard data but also on public attitudes and experiences. It tries to incorporate wealth and well-being.
So, how do we do?
I don't know if you remember a TV show in the mid-'80s presented by Fleet Street veteran Derek Jameson entitled Do They Mean Us? It showed clips from around the world about Britain, about how others see us.
Reading the Legatum Institute data I am reminded of that because, viewed in a global context, Britain is a very different country from the one we might imagine.
Let me give you a couple of examples.
While UK politics has been gripped by debates about civil liberties and immigration, today's survey suggests we have "extremely high levels" of civil liberties in comparison to other countries, we rank "high in terms of perceived tolerance for immigrants" and there is "very high tolerance for racial and ethnic minorities".
Broken Britain? Not based on this report. UK citizens are "highly engaged in society", it says. We come second in the world when it comes to people believing they can rely on relatives and friends for help, and our trust levels are firmly in the world's top 20.
Britain has the fourth-largest proportion of people who give to charity. A slightly above average 53% of Britons are married.
When you look at the detail which informs our global ranking, it is often public attitudes rather than hard data that pulls us down.
In international terms, we have "high levels" of safety and security, but our score suffers because of public perceptions of the risk. Internationally, the chances of being assaulted in Britain are "low" but the UK ranks 40th in terms of citizens feeling safe walking home alone at night.
When it comes to another key measure, governance, the report finds Britain has "a highly effective government", a "robust democracy" and "low levels of corruption". But that is not what people think. Britain comes 74th in the world in terms of confidence in our government, again, dragging our overall score down.
The survey work was done last year, after the MPs expenses scandal and just as the banking crisis was pushing the world into recession.
On the economy, the data shows Britain has the fifth-largest market in the world, 20% of our manufactured goods are high-tech exports, we score well on inflation, well on affordability of food and shelter, and in the top 10 for people's satisfaction with their standard of living.
But read what the Legatum Institute press release says about our faith and optimism for the British economy:
"Of the 110 countries covered by the survey, Britain ranks a staggering 101st on public confidence in financial institutions, 98th on optimism about job prospects and 93rd on expectations of future economic performance - the kind of ratings usually found in the world's poorest countries."
Why are we British so much more distrusting of financial and political institutions than other wealthy, healthy and successful nations? Is it our adversarial culture? Is it an aggressive media? Is it the weather?
Overall, we are the 13th most prosperous country in the world by this index, but I can't help feeling that if we were slightly less gloomy and cynical we could give some of those Nordic countries, which always top surveys like this, a run for their money.