We had only limited data on potential confounders, and information on potentially important risk factors, such as maternal smoking habits and gestational age, was not available.
Based on a generic typology green spaces were mapped and linked with information on potentially provided ES and their parameters.
We present an approach to investigating causal mechanisms in survey experiments that leverages the provision or withholding of information on potentially important mediating variables.
This is a very large study with virtually complete follow-up and with detailed information on potentially important confounders including smoking, deprivation, reproductive and hormonal factors, body size, dietary factors, and other health indicators.
Seena Fazel, professor of forensic psychiatry at Oxford University, added: "The problem with this specific study is that the authors don't have the necessary information on potentially important background factors, which in this case will be genetic risks for autism".
Privacy rights group Privacy International says it has obtained evidence for the first time that UK spy agencies are collecting social media information on potentially millions of people.
