We have an idea, but the data is patchy and complex.
In some subjects, the data is patchy as student returns fall below statistically acceptable levels.
But historical cross-country comparisons are difficult to make; the data are patchy, and different countries measure differently.
Although the data is patchy at best it appears these cuts have coincided with deteriorating mental health among young people.
Data are patchy but suggest that start-ups do deliver better results.
Since trafficking is run by illegal gangs and the communities involved are poor and remote, official data is patchy and probably underestimates the scale of the problem, according to experts.
In an average American hospital, that figure would have fallen to 16% and (though the data is patchy) roughly the same, or less, if your heart were to have stopped beating in a British hospital.
Kevin Trenberth of America's National Centre for Atmospheric Research (NCAR), who co-ordinated the relevant part of the 2007 IPCC report, claims the study is skewed by the way the authors calculate the influence of humidity, wind and clouds on which data are patchy.
Data are patchy, but according to new figures from the China-Latin America Finance Database, a joint effort between the Inter-American Dialogue, a think-tank, and Boston University, China committed almost $100 billion to Latin America between 2005 and 2013 (see chart).
The single mothers left to do the job now swell the growing ranks of the poor, and have little hope, except in remarriage, of ever doing better.The data are patchy, but a recent survey by the Russian Academy of Sciences says that 28% of all children are born to unwed mothers.
