In a recent paper in the Journal of Economics Perspectives, Philip Levine and Melissa Kearney use some novel techniques and data on miscarriages to ask whether teenage mums have children because they are poor or are they poor because they have children (their paper is available here and you can read Slate's coverage here). Interestingly, their evidence seems to indicate that teenage girls have children because they live in impoverished circumstances with poor future prospects. This, of course, raises questions about the future prospects of the offspring of teenage mothers. What role can public policy play in dealing with this issue? Does rising inequality and reduced social mobility make it harder for poor teenagers to escape the poverty trap?
The Berkeley Earth Project , an independent study of global warming, has found that the earth has become a degree warmer over the past half century. However, the statistical uncertainty surrounding pre-1920 estimates makes it very hard to say much about long-term trends - click here for graph . This is one of my concerns with the global warming debate - we simply don't have trustworthy long-run data which looks at temperature changes over the last millennium (or two). My second concern with the global warming debate is that it is very hard to prove any sort of casual link between global warming and human activity. The scientists may be able to show correlation between global warming and our production of carbon dioxides etc., but correlation is not causation. My third concern with the debate is that those who are sceptical or agnostic are stereotyped as flat-earthers or intellectually-challenged crackpots. This only stifles debate and the progress of science itself.