Como mentir com índices de performance internacional

“CROOKS already know these tricks. Honest men must learn them in self-defence,” wrote Darrell Huff in 1954 in “How to Lie With Statistics”, a guide to getting figures to say whatever you want them to. Sadly, Huff needs updating.

The latest way to bamboozle with numbers is the “performance index”, which weaves data on lots of measures into a single easy-to-understand international ranking. From human suffering to perceptions of corruption, from freedom to children’s happiness, nowadays no social problem or public policy lacks one (see article). Governments, think-tanks and campaigners love an index’s simplicity and clarity; when well done, it can illuminate failures, suggest solutions and goad the complacent into action. But there are problems. Competing indices jostle in the intellectual marketplace: the World Economic Forum’s Global Gender Gap ranking, published last week, goes head to head with the UN’s Gender Inequality Index, the Index of Women’s Power from Big Think, an internet forum—and even The Economist’s own Glass Ceiling Index. Worse, some indices are pointless or downright misleading.

As easy as 1, 2, 3

Which to trust, and which to ignore? In the spirit of Huff, here is our guide to concocting a spurious index. Use it to guard against guile—or follow it to shape public perceptions and government policies armed only with a catchy title, patchy data and an agenda.

First, banish pedantry and make life easier for yourself by using whatever figures are to hand, whether they are old, drawn from small or biased samples, or mixed and matched from wildly differing sources. Are figures for a country lacking? Use a “comparator”, no matter how dubious; one index of slavery, short of numbers for Ireland and Iceland, uses British figures for both (aren’t all island nations alike?). If the numbers point in the wrong direction, find tame academics and businessfolk to produce more convenient ones, and call their guesses “expert opinion”. If all that still fails to produce what you want, tweak the weighting of the elements to suit.

Get the presentation right. Leaving your methodology unpublished looks dodgy. Instead, bury a brief but baffling description in an obscure corner of your website, and reserve the home page for celebrity endorsements. Get headlines by hamming up small differences; minor year-on-year moves in the rankings may be statistical noise, but they make great copy.

Above all, remember that you can choose what to put in your index—so you define the problem and dictate the solution. Rankings of business-friendliness may favour countries with strict laws; don’t worry if they are never enforced. Measures of democracy that rely on turnout ignore the ability of autocrats to get out the vote. Indices of women’s status built on education levels forget that, in Saudi Arabia, women outnumber men in universities because they are allowed to do little else but study. If you want prostitution banned, count sex workers who cross borders illegally, but willingly, as “trafficking victims”. Criticism can always be dismissed as sour grapes and special pleading. The numbers, after all, are on your side. You’ve made sure of that.


Fonte: aqui
From the print edition: Leaders