By Dr. Alexander Dill
Suppose you had ten teams of high class scientists assessing the same 141 countries each by its own criteria without knowing each other. One team is assessing ‘enabling environment’, others estimate ‘competitiveness’, ‘human development’, ‘social progress’, ‘prosperity’, ‘giving’, ‘ecological footprint’ and ‘peace’. Team no. 10 is assessing the progress of countries in meeting the 17 Sustainable Development Goals (SDGs) approved at the UN.
After their assessment they publish their country ranking from 1 to 141. If two of these indexes rank the same countries in the same order, a statistician will say they are “redundant”, which means that somehow they ended up measuring the same thing even if under different names or through different proxies. If one index ranks a country as number 1 and the other as 141, the statistician will observe that this country has the maximum possible “standard deviation” (which in this case is 70). If we have ten independent teams measuring ten different things we can expect some of the results to be redundant (for example, better education for girls correlates with lower infant and maternal mortality), while others show deviation: low income equality, for example, can be found both in very rich and very poor countries. Read more…